DigitallyCreated Utilities is set of open source libraries that contain some simple (and not so simple) utilities and extensions developed in C# that make working in .NET easier. There are classes to help when working with LINQ, Entity Framework, ASP.NET MVC and Unity Application Block. There are also some nice extensions that replace missing functionality in the .NET Base Class library, and some utilities that enable you to write concurrent (threaded) applications more easily.
DigitallyCreated Utilities is hosted on CodePlex. You will find the binaries, source code, tutorials and documentation there.