To those unfamiliar, javabat is a website that hosts dozens of small java coding tasks. You write an implementation, the site compiles the code, and you get immediate feedback on whether your answer was correct. In my opinion it’s an excellent resource for those learning the language (and long-time java coders who want to keep their low-level skills sharp).
Is there anything similar to this in the C# world?
I would check out Compilr:
Also MSDN Virtual Labs:
Also you could check out CodeRun’s IDE.