dotPeek is a free .NET decompiler, which can decompile .NET assemblies to c# codes. This utility supports framework 1.0 to 4.5. earlier we have posted about this software while it was in beta , you can read that - dotPeek - Free .NET decompiler.
The latest version 1.1 have some more features
Exposrt assembly to project, you can save the decompiled assemblies to Visual studio projects.
Better LINQ, Async codes and lambda support
Decompile assemblies to C# code including .dll, .exe, .baml and .winmd
Save decompiled codes as Visual studio projects
Find usage of functions, property, local variable etc.
Based on local pdb files find source code
Overview of inheritance chains
Explore current class
Complete keyboard support
JetBrains dotPeek is will be a useful tool is you are looking for a free .NET decompiler. You can get it from here dotPeek free .NET decompiler