My implementation of http://blog.stevensanderson.com/2010/01/28/editing-a-variable-length-list-aspnet-mvc-2-style/

Details.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<CHSweb.Models.ViewModels.PropertyDetailsViewModel>" %>
<%@ Import Namespace="CHSweb.Helpers" %>
<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
	Details
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="HeadContent" runat="server">
	<script src="/Scripts/jquery.form.js" type="text/javascript"></script>
	<script src="/Scripts/PropertyEditor.js" type="text/javascript"></script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
	<div>
		<h1><%: Model.Property.Name %></h1>
		<div>
			<%: Html.Hidden("propertyId", Model.Property.Id) %>
			<% Html.RenderPartial("OperatingStatementList", Model.OperatingStatements); %>
		</div>
</asp:Content>

HtmlPrefixScopeExtensions.cs

public static class HtmlPrefixScopeExtensions
{
	private const string idsToReuseKey = "__htmlPrefixScopeExtensions_IdsToReuse_";

	public static IDisposable BeginCollectionItem(this HtmlHelper html, string collectionName)
	{
		var idsToReuse = GetIdsToReuse(html.ViewContext.HttpContext, collectionName);
		string itemIndex = idsToReuse.Count > 0 ? idsToReuse.Dequeue() : Guid.NewGuid().ToString();

		// autocomplete="off" is needed to work around a very annoying Chrome behaviour whereby it reuses old values after the user clicks "Back", which causes the xyz.index and xyz[...] values to get out of sync.
		html.ViewContext.Writer.WriteLine(string.Format("<input type=\"hidden\" name=\"{0}.index\" autocomplete=\"off\" value=\"{1}\" />", collectionName, html.Encode(itemIndex)));

		return BeginHtmlFieldPrefixScope(html, string.Format("{0}[{1}]", collectionName, itemIndex));
	}

	public static IDisposable BeginHtmlFieldPrefixScope(this HtmlHelper html, string htmlFieldPrefix)
	{
		return new HtmlFieldPrefixScope(html.ViewData.TemplateInfo, htmlFieldPrefix);
	}

	private static Queue<string> GetIdsToReuse(HttpContextBase httpContext, string collectionName)
	{
		// We need to use the same sequence of IDs following a server-side validation failure,  
		// otherwise the framework won't render the validation error messages next to each item.
		string key = idsToReuseKey + collectionName;
		var queue = (Queue<string>)httpContext.Items[key];
		if (queue == null) {
			httpContext.Items[key] = queue = new Queue<string>();
			var previouslyUsedIds = httpContext.Request[collectionName + ".index"];
			if (!string.IsNullOrEmpty(previouslyUsedIds))
				foreach (string previouslyUsedId in previouslyUsedIds.Split(','))
					queue.Enqueue(previouslyUsedId);
		}
		return queue;
	}

	private class HtmlFieldPrefixScope : IDisposable
	{
		private readonly TemplateInfo templateInfo;
		private readonly string previousHtmlFieldPrefix;

		public HtmlFieldPrefixScope(TemplateInfo templateInfo, string htmlFieldPrefix)
		{
			this.templateInfo = templateInfo;

			previousHtmlFieldPrefix = templateInfo.HtmlFieldPrefix;
			templateInfo.HtmlFieldPrefix = htmlFieldPrefix;
		}

		public void Dispose()
		{
			templateInfo.HtmlFieldPrefix = previousHtmlFieldPrefix;
		}
	}
}

OperatingStatementEditorRow.ascx

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<CHSweb.Data.Models.OperatingStatement>" %>
<%@ Import Namespace="CHSweb.Helpers" %>
<div id="operatingStatementFormContainer">
	<% using (Html.BeginCollectionItem("operatingStatements")) { %>
	<%: Html.ValidationSummary(true) %>
	<fieldset>
		<legend>Fields</legend>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.Year) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.Year) %>
			<%: Html.ValidationMessageFor(model => model.Year) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RoomsAvailable) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RoomsAvailable) %>
			<%: Html.ValidationMessageFor(model => model.RoomsAvailable) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RoomsOccupied) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RoomsOccupied) %>
			<%: Html.ValidationMessageFor(model => model.RoomsOccupied) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.Occupancy) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.Occupancy) %>
			<%: Html.ValidationMessageFor(model => model.Occupancy) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.ADR) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.ADR) %>
			<%: Html.ValidationMessageFor(model => model.ADR) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RoomRevenue) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RoomRevenue) %>
			<%: Html.ValidationMessageFor(model => model.RoomRevenue) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RBRevenue) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RBRevenue) %>
			<%: Html.ValidationMessageFor(model => model.RBRevenue) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.OtherOperatingDepartmentRevenue) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.OtherOperatingDepartmentRevenue) %>
			<%: Html.ValidationMessageFor(model => model.OtherOperatingDepartmentRevenue) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RentalsAndOtherIncome) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RentalsAndOtherIncome) %>
			<%: Html.ValidationMessageFor(model => model.RentalsAndOtherIncome) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.RoomsExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.RoomsExpense) %>
			<%: Html.ValidationMessageFor(model => model.RoomsExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.FBExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.FBExpense) %>
			<%: Html.ValidationMessageFor(model => model.FBExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.OtherOperatingDepartmentExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.OtherOperatingDepartmentExpense) %>
			<%: Html.ValidationMessageFor(model => model.OtherOperatingDepartmentExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.AGExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.AGExpense) %>
			<%: Html.ValidationMessageFor(model => model.AGExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.SalesMarketingExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.SalesMarketingExpense) %>
			<%: Html.ValidationMessageFor(model => model.SalesMarketingExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.FranchiseFees) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.FranchiseFees) %>
			<%: Html.ValidationMessageFor(model => model.FranchiseFees) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.POMExpense) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.POMExpense) %>
			<%: Html.ValidationMessageFor(model => model.POMExpense) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.UtilityCost) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.UtilityCost) %>
			<%: Html.ValidationMessageFor(model => model.UtilityCost) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.ManagementFee) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.ManagementFee) %>
			<%: Html.ValidationMessageFor(model => model.ManagementFee) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.PropertyTax) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.PropertyTax) %>
			<%: Html.ValidationMessageFor(model => model.PropertyTax) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.Insurance) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.Insurance) %>
			<%: Html.ValidationMessageFor(model => model.Insurance) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.EquipmentLease) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.EquipmentLease) %>
			<%: Html.ValidationMessageFor(model => model.EquipmentLease) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.GroundLease) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.GroundLease) %>
			<%: Html.ValidationMessageFor(model => model.GroundLease) %>
		</div>
		<div class="editor-label">
			<%: Html.LabelFor(model => model.Other) %>
		</div>
		<div class="editor-field">
			<%: Html.TextBoxFor(model => model.Other) %>
			<%: Html.ValidationMessageFor(model => model.Other) %>
		</div>
		<p>
			<input type="submit" value="Create" />
		</p>
	</fieldset>
	<% } %>
</div>

OperatingStatementList.ascx

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<CHSweb.Data.Models.OperatingStatement>>" %>
<div class="listSection">
	<h4>Operating Statements</h4>
	<% using (Html.BeginForm("AddOperatingStatement", "Property", FormMethod.Post, new { id = "operatingStatementForm" })) { %>
	<table>
		<thead>
			<tr>
				<th>Year</th>
				<th>Occupancy</th>
				<th>Room Revenue</th>
				<th>Rooms Expense</th>
				<th>AG Expense</th>
				<th></th>
			</tr>
		</thead>
		<tbody id="operatingStatementRows">
			<% foreach (var operatingStatement in Model)
				Html.RenderPartial("OperatingStatement", operatingStatement);
			%>
		</tbody>
	</table>
	<%= Html.ActionLink("New Operating Statement", "BlankOperatingStatementRow", null, new { id = "addOperatingStatement" })%>
	<% } %>
</div>

OperatingStatment.ascx

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<CHSweb.Data.Models.OperatingStatement>" %>
<tr>
	<td><%: Model.Year %></td>
	<td><%: Model.Occupancy %></td>
	<td><%: Model.RoomRevenue.GetValueOrDefault().ToString("C" )%></td>
	<td><%: Model.RoomsExpense.GetValueOrDefault().ToString("C") %></td>
	<td><%: Model.AGExpense.GetValueOrDefault().ToString("C") %></td>
	<td><%: Html.ActionLink("Delete", "Delete", "OperatingStatement", new { id = Model.Id }, new { @class = "deleteLink" } )%></td>
</tr>

PropertyController.cs

public class PropertyController : Controller {

	CHSDataContext db = new CHSDataContext(ConfigurationManager.ConnectionStrings["chsdb"].ConnectionString);

	[HttpPost]
	public ActionResult AddOperatingStatement(int propertyId, IEnumerable<OperatingStatement> operatingStatements) {
		try {
			var operatingStatement = operatingStatements.First();
			operatingStatement.PropertyId = propertyId;
			db.OperatingStatements.InsertOnSubmit(operatingStatement);
			db.SubmitChanges();
			return View("OperatingStatement", operatingStatement);
		} catch {
			return Json("Error");
		}
	}

	public ViewResult BlankOperatingStatementRow() {
		return View("OperatingStatementEditorRow", new OperatingStatement());
	}
}

PropertyEditor.js

function getPropertyId() {
	return $("#propertyId").val();
}

$(document).ready(function () {
	$("#addOperatingStatement").click(function () {
		$.ajax({
			url: this.href,
			cache: false,
			success: function (html) {
				$("#operatingStatementRows").append(html);
				$("#operatingStatementForm").ajaxForm({
					target: '#operatingStatementFormContainer',
					replaceTarget: true,
					data: { propertyId: getPropertyId() }
				});
			}
		});
		return false;
	});
});