Red Gate  will be responsible for the future development  of .NET Reflector , the popular tool authored by Lutz Roeder . I’m very happy to read that Red Gate will offer this tool for free to the community. Lutz did a great job and the feedback from developers around the world brings up this tool to the top 10 tools for .NET developers .
Use Reflector if you need to:
- Explore .NET assemblies in an easy-to-understand, natural way
- Understand the relationships between classes and methods
- Find where types are instantiated and exposed
- Check that your code has been correctly obfuscated before release
- ...or if you have lost your source code and have still the DLL/EXE (well, that was one reason I was very happy that .NET Reflector exists)
At codeplex.com you’ll find more than 30 add-ins for .NET Reflector . My favorite one is the FileDisassembler  from Denis Bauer .