gistfile1.cs

    using System;
    using System.Collections.Specialized;
    using System.Linq;
    using System.Net;

    class Example
    {
        public static void Main (string[] args)
        {
            Subscribe(1905, "scott@kickofflabs.com");    
        }

        public static string Subscribe(int landingPageId, string email, NameValueCollection arguments = null)
        {
            arguments = arguments ?? new NameValueCollection();
            arguments.Add("email", email);
            
            var queryString = "?" + String.Join("&", arguments.AllKeys
                    .Select(item => item + "=" + String.Join(",", arguments.GetValues(item))));

            var url = string.Format("http://api.kickofflabs.com/v1/{0}/subscribe", landingPageId);

            using (var client = new WebClient())
            {
                try
                {
                    return client.UploadString(url, queryString);
                }
                catch (WebException)
                {
                    return "Could not subscribe the email address " + email;
                }
            }
        }
    }