BitTorrent.net
If you need to implement bittorrent functionality in your .NET application, you will most likely come across btsharp in your initial googling. However, if you do manage to get the site to load and download the source/dlls you will notice that they are all designed to work with VS.NET 2005. After much frustration and many google queries, I now present you with an alternative that works fine with Visual Studio 2003: BitTorrent.net. Initial tests show the torrent files downloading perfectly.
http://www.gotdotnet.com/workspaces/workspace.aspx?id=415e48ec-f860-4ea1-8f31-abc7cf1644c7
"What," might you ask, "am I using this for?" Well, I'm sure I'll let you know shortly :).