GetAccountProfilePicture.cs

using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;

namespace GetAccountProfilePicture
{
    class Program
    {

        [DllImport("shell32.dll", EntryPoint = "#261",
               CharSet = CharSet.Unicode, PreserveSig = false)]
        public static extern void GetUserTilePath(
      string username,
      UInt32 whatever, // 0x80000000
      StringBuilder picpath, int maxLength);

        public static string GetUserTilePath(string username)
        {   // username: use null for current user
            var sb = new StringBuilder(1000);
            GetUserTilePath(username, 0x80000000, sb, sb.Capacity);
            return sb.ToString();
        }

        public static Image GetUserTile(string username)
        {
            return Image.FromFile(GetUserTilePath(username));
        }

        static void Main(string[] args)
        {
            string uname = System.Security.Principal.WindowsIdentity.GetCurrent().Name.Split('\\').Last();
            Image img = GetUserTile(uname);
            img.Save(Environment.GetFolderPath(Environment.SpecialFolder.Desktop)+"\\pic.png", ImageFormat.Png);
        }
    }
}