.NET compiler for the LOLCode language.
LOLCode is an emerging esoteric (and hilarious) language based on the dialect used in LOLCats images. It's been siezed upon by a group of people (myself included, now), and is being expanded into a real, workable, turing complete esoteric language (though nobody has proven its turing completeness yet!).
The LOLCode.NET compiler is now working, and as a nearly-free bonus for using the .NET platform, you can even debug it in Visual Studio:
I still can't believe I'm looking at LOLCode and its x86 disassembly in Visual Studio.