controller.cs

public ActionResult SiteMap()
		{
			var items = new List<SiteMapItem>
			{
				new SiteMapItem("Index", "Serial", SiteMapChangeFreq.Daily, 1.0f),
				new SiteMapItem("About", "Home", SiteMapChangeFreq.Monthly, 1.0f),
				new SiteMapItem("Register", "Account", SiteMapChangeFreq.Monthly, 0.9f),
				new SiteMapItem("Login", "Account", SiteMapChangeFreq.Monthly, 0.9f),
				new SiteMapItem("Changelog", "Home", SiteMapChangeFreq.Monthly, 0.9f),
				new SiteMapItem("Donate", "Home", SiteMapChangeFreq.Never, 0.9f)
			};

			RepositorySpecial.FetchAllSerialIds().ForEach(i =>
				items.Add(new SiteMapItem("Detail", "Serial", new { id = i }, SiteMapChangeFreq.Weekly, 0.8f)));

			int episodesCount = RepositoriesFactory.EpisodeRepository.Count(new ReleasedEpisodesQuery());
			int pages = episodesCount / DEFAULT_PAGE_SIZE + (episodesCount % DEFAULT_PAGE_SIZE == 0 ? 0 : 1);
			for (int i = 2; i <= pages; i++)
			{
				items.Add(new SiteMapItem("Index", "Serial", new { id = i }, SiteMapChangeFreq.Daily, 0.7f));
			}

			return new SiteMapResult(items);
		}

ISiteMapItem.cs

using System.Web.Mvc;

namespace SerialTracker.Web.SiteMap
{
	public interface ISiteMapItem
	{
		string GetAddress(UrlHelper Url, string siteAddress);

		string ChangeFreq
		{
			get;
			set;
		}

		float Priority
		{
			get;
			set;
		}
	}
}

SiteMapChangeFreq.cs

namespace SerialTracker.Web.SiteMap
{
	public static class SiteMapChangeFreq
	{
		public static string Always
		{
			get
			{
				return "always";
			}
		}

		public static string Hourly
		{
			get
			{
				return "hourly";
			}
		}

		public static string Daily
		{
			get
			{
				return "daily";
			}
		}

		public static string Weekly
		{
			get
			{
				return "weekly";
			}
		}

		public static string Monthly
		{
			get
			{
				return "monthly";
			}
		}

		public static string Yearly
		{
			get
			{
				return "yearly";
			}
		}

		public static string Never
		{
			get
			{
				return "never";
			}
		}
	}
}

SiteMapItem.cs

using System.Web.Mvc;
namespace SerialTracker.Web.SiteMap
{
	public class using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using System.Xml;
using System.Web;

namespace SerialTracker.Web.SiteMap
{
	public class SiteMapResult : ActionResult
	{
		private List<ISiteMapItem> _items;

		public SiteMapResult(IEnumerable<ISiteMapItem> items)
			:this(items.ToList())
		{
		}

		public SiteMapResult(List<ISiteMapItem> items)
		{
			_items = items;
		}

		public override void ExecuteResult(ControllerContext context)
		{
			XmlWriterSettings settings = new XmlWriterSettings();
			UrlHelper Url = new UrlHelper(context.HttpContext.Request.RequestContext);
			settings.Indent = true;
			settings.NewLineHandling = NewLineHandling.Entitize;

			context.HttpContext.Response.ContentType = "text/xml";
			using (XmlWriter _writer = XmlWriter.Create(context.HttpContext.Response.OutputStream, settings))
			{
				
				// Begin structure
				_writer.WriteStartElement("urlset","http://www.sitemaps.org/schemas/sitemap/0.9");
				_writer.WriteAttributeString("xmlns", "xsi", null, "http://www.w3.org/2001/XMLSchema-instance");
				_writer.WriteAttributeString("xsi", "schemaLocation", null, "http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd");

				// Individual items
				_items.ForEach(x =>
				{
					_writer.WriteStartElement("url");
					_writer.WriteElementString("loc",
						x.GetAddress(Url, context.HttpContext.Request.Url.GetLeftPart(UriPartial.Authority)));
					_writer.WriteElementString("changefreq", x.ChangeFreq);
					_writer.WriteElementString("priority", x.Priority.ToString("0.00").Replace(",", "."));
					_writer.WriteEndElement();
				});

				// End structure
				_writer.WriteEndElement();
			}
		}
	}
} : ISiteMapItem
	{
		public SiteMapItem(string action, string controller, string changefreq, float prior = 0.5f)
			: this(action, controller, null, changefreq, prior)
		{
		}

		public SiteMapItem(string action, string controller, object routevalues, string changefreq, float prior = 0.5f)
		{
			this.Action = action;
			this.Controller = controller;
			this.RouteValues = routevalues;
			this.ChangeFreq = changefreq;
			this.Priority = prior;
		}

		public string GetAddress(UrlHelper Url, string siteAddress)
		{
			return siteAddress + Url.Action(Action, Controller, RouteValues);
		}

		public string Action
		{
			get;
			set;
		}

		public string Controller
		{
			get;
			set;
		}

		public object RouteValues
		{
			get;
			set;
		}

		public string ChangeFreq
		{
			get;
			set;
		}

		public float Priority
		{
			get;
			set;
		}
	}
}

SiteMapResult.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using System.Xml;
using System.Web;

namespace SerialTracker.Web.SiteMap
{
	public class SiteMapResult : ActionResult
	{
		private List<ISiteMapItem> _items;

		public SiteMapResult(IEnumerable<ISiteMapItem> items)
			:this(items.ToList())
		{
		}

		public SiteMapResult(List<ISiteMapItem> items)
		{
			_items = items;
		}

		public override void ExecuteResult(ControllerContext context)
		{
			XmlWriterSettings settings = new XmlWriterSettings();
			UrlHelper Url = new UrlHelper(context.HttpContext.Request.RequestContext);
			settings.Indent = true;
			settings.NewLineHandling = NewLineHandling.Entitize;

			context.HttpContext.Response.ContentType = "text/xml";
			using (XmlWriter _writer = XmlWriter.Create(context.HttpContext.Response.OutputStream, settings))
			{
				
				// Begin structure
				_writer.WriteStartElement("urlset","http://www.sitemaps.org/schemas/sitemap/0.9");
				_writer.WriteAttributeString("xmlns", "xsi", null, "http://www.w3.org/2001/XMLSchema-instance");
				_writer.WriteAttributeString("xsi", "schemaLocation", null, "http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd");

				// Individual items
				_items.ForEach(x =>
				{
					_writer.WriteStartElement("url");
					_writer.WriteElementString("loc",
						x.GetAddress(Url, context.HttpContext.Request.Url.GetLeftPart(UriPartial.Authority)));
					_writer.WriteElementString("changefreq", x.ChangeFreq);
					_writer.WriteElementString("priority", x.Priority.ToString("0.00").Replace(",", "."));
					_writer.WriteEndElement();
				});

				// End structure
				_writer.WriteEndElement();
			}
		}
	}
}