Reflexil - Reflexil is a Reflector Add-In which allows you to modify assemblies using Mono.Cecil

Reflexil is an assembly editor and runs as a plug-in for Red Gate's Reflector and Telerik's JustDecompile. Reflexil is using Mono.Cecil, written by Jb Evain and is able to manipulate IL code and save the modified assemblies to disk. Reflexil also supports C#/VB.NET code injection.