SharpDevelop is an full-featured, open-sourced IDE for .NET development. Version 2.0 is out and is definitely worth a look! I used the previous version, but found the lack of integrated debugging to be a serious limitation. But the 2.0 version has integrated debugging.

For those of you supporting previous versions of the .NET framework, SharpDevelop can be configured to compile for .NET 1.0, 1.1, or 2.0.

Clickhere for a feature tour of SharpDevelop 2.0.

Check out SharpDevelop 2.0here.