Any one who programs in .NET is well aware of Lutz Roeder's .NET Reflector. It is a tool which allows you to disassemble .NET assemblies in to IL, C#, Visual Basic and several other languages. This tool also supports many add-ins which add cool features to it. Today I came across one that I had been wanting for a while. It is called Reflexil and it allows you to modify the code of an existing assembly. You can modify any of the IL and it even is beginning to support rewriting in C# or VB parts of the existing assembly.