LINQ – Language Integrated Query

MSDN: http://msdn.microsoft.com/en-us/library/bb397676(v=VS.100).aspx
          http://msdn.microsoft.com/en-us/library/bb397926(v=VS.100).aspx

101 Samples: http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx

LINQ Pad: http://www.linqpad.net/

Entity – LINQ: http://blogs.msdn.com/b/brunoterkaly/archive/2010/01/25/ado-net-entity-framework-and-net-4-how-to-use-visual-studio-2010-modeling-tools-to-build-a-database.aspx