Creating dynamic LINQ queries

Dynamic LINQ library:
http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
More object-oriented approach - with all goodies of the modern .NET in one mix: generics, extension methods and LINQ:
http://talentgrouplabs.com/blog/archive/2007/11/26/dynamic-linq-queries--dynamic-where-clause-part-2.aspx
Same stuff with a little different samples from Joseph Albahari:
http://www.albahari.com/nutshell/predicatebuilder.aspx