IL IDA tool

A little interactive disassembly for you from the Reflector addins.

Reflexil on SourceForge.net

Reflexil is an assembly editor and runs as a plug-in for Reflector. Using Mono.Cecil, Reflexil is able to manipulate IL code and save the modified assemblies to disk. Reflexil also supports 'on the fly' C# and VB.NET code injection.