.Net 2.0 Code Conversion
This one is Cool. The Sharp Develop folks has a code convertor out that works for .Net 2.0 (including generics!) and it works for C# <-> VB.Net and VB.Net / C# -> Boo!
You can get it here, and there is even a web service you can call to do it automatically from your code. I like the design of only converting to Boo, obviously once you've got your code in Boo, you never need to move it to another language.
This convertor uses the NRefactory library, so it's pretty robust, and the code it generates is legible.