Salamander is a .NET decompiler that converts executable files (.EXE or .DLL) from Intermediate Language (IL) binary format to high-level source codes, such as C#, managed C++, Visual Basic.NET, etc. For more than 8,000 classes that have been tested, Salamander always produces equivalent and recompilable codes that are remarkably close to the original source codes.
you can visit & try it online here
Another very interesting decomplier is Ankarino, a very powerful command line tool which is provided as an open source utility, so you can get under the covers and see how it works.
give it a whirl here