LINQPad lets you interactively query SQL databases in a modern query language: LINQ.
LINQPad supports everything in C# 3.0 and Framework 3.5:
- LINQ to SQL
- LINQ to Objects
- LINQ to XML
LINQPad is also a great way to learn LINQ: it comes preloaded with 200 examples from the book, C# 3.0 in a Nutshell.
Want to look at a preview of How LINQPad looks like, here it is: