Chris Sells has a bunch of free tools (some .NET) available on his website. Here is the skinny on a couple of them:

1. In writing the resources chapter of my WinForms book, I found that there was no single utility for displaying the resource contents of assemblies, .resx files and .resource files (even embedded .resources files) in a way that made sense to me. So, I built one and called it ResourceExplorer.
2. Scancode Mapper is a GUI tool for setting the Scan Code Mapper for Windows Registry settings for Win2K+:
3. XsdClassesGen is a Custom Tool Add-In to VS.NET to generate type-safe wrapper classes for serializing to and from XML documents.
4. CollectionGen is a Custom Tool Add-In to VS.NET to generate type-safe collections.
5. RegexDesigner.NET is a powerful visual tool for helping you construct and test .NET Regular Expressions.

There are actually more on this page.

Are there other free .NET tools out there that you'd like to let folks know about? If so, post a comment with some links so we can all share in the wealth of free tools available.