LINQPad supports everything in C# 3.0 and Framework 3.5:
- LINQ to SQL
- LINQ to Objects
- LINQ to XML
LINQPad is also a terrific tool for learning LINQ: it comes preloaded with 200 examples from the recently released C# 3.0 in a Nutshell. There’s no better way to experience the coolness of LINQ and functional programming.