Today, Keith Dahlby and Wictor Wilén released v2.0 of the sharepoint extensions library, which contains some really helpful functions for sharepoint development.
Please take a look at http://solutionizing.net/2009/06/01/spexlib-release-these-are-a-few-of-my-favorite-things/ for a post with some personal favorite functions of keith.
Thanks guys, for sharing this with us!