LinqPad, stand alone Win application [
^]. Free and paid (Pro, Premium) versions. Recommended.
Linq Insight: commercial db oriented [
^].
I have not used MS's Object Relational Designer in VS 2010, 2012, or 2013: [
^].
Visual LINQ Query Builder, integrated with Visual Studio 2008 [
^]. Done by MS interns in 2008. Evidently cannot install in VS 2010. I can verify you cannot install in Win 8 with VS 2012, and 2013 installed. Not recommended.