http://somewebguy.wordpress.com/2009/07/08/jlinq-screencast-2-creating

jLinq is a Javascript library that allows you to do LINQ style queries with JSON data. Did you know that jLinq let’s you extend the base library with your own methods? Did you realize that any method you create plugs right in and works with the built in jLinq features? This screencast goes over some of the basics to creating your first extension method for jLinq.