Hey there- I recently finished up a plugin that I think has the potential to be really useful for folks. It uses jQuery's excellent selector support to work around some of the crummy CSS selector support in legacy browsers.
If you've ever had to spend time adding 'class="radio"' to all the radio buttons on your site, this plugin is for you. If you've ever had to add 'class="first"' to an list item because not all of your target browsers support 'li:first', this plugin is for you. If you've ever had to add any class to your markup simply to work around CSS selector support, this plugin is for you. I've posted a novice-friendly writeup at http://skulljackpot.com/2009/04/19/super-css-selector-support-with-jquery/ - but you can also pull the code directly from github at http://github.com/chrispatterson/jquery-super-selectors/tree/master There are some additional enhancements I've been kicking around, but I'd love to hear feedback from folks about how to make this more useful for their particular needs. Chris