One of our OEMs provides an FTP server that is built in C and compiled against Windows CE 4.2.  The new version of a another device that connects to this server via its own FTP client no longer works for some reason, this 2nd OEM claims that some timeout or tolerance in the device is too touchy and that it simply cannot speak to this FTP server.  Doing some searching I found a partial FTP RFC implementation originally posted on gotdotnet and authored by a gentleman by the name of joel@collude.com.au.   There doesn't appear to be any open source license present so I got the source, hacked it to run on the CF, removed a cumbersome custom logging interface to replace it with the CF version of log4net, and cleaned up deprecated code warnings for CF2.0.  The idea was I would send the OEM a log of FTP server sessions to determine which tolerences needed to be increased, but the device in question talks fine to my new custom FTP server running on CE.  I continue to be a big fan of the performance of .NET.

Up to this point I usually don't make full source available with articles but I'm thinking I should change that policy once I've chosen an appropriate open source license.  Would anyone like an FTP implementation in C#?