If you're like me and often check out small snippets of code and end up with a bunch of single file VS.Net projects then be sure to check out SnippetCompiler from Jeff Key. This little gem is a like a mini development environment that compiles code on the fly and lets you run it without creating any sort of project. Perfect for those quick single file tests.

It also generates HTML output from code with syntax color highlighting which is nice for pasting into messages.

Awesome and it comes with source to boot.