You may even know non less awesome SQL Fiddle using which you can build custom schemas, tables, views and run and share your SQL queries in various RDBMS.
But have you heard about .NET Fiddle? This is a great interactive compiler, using IDE familiar to other fiddlers users it allows you to run and share your .NET code in both C# and VB.NET.
From the developers of .NET Fiddle:
We are a group of .NET developers who are sick and tired of starting Visual Studio, creating a new project and running it, just to test simple code or try out samples from other developers.
Give it try!