cssQuery() is a powerful cross-browser JavaScript function that enables querying of a DOM document using CSS selectors. All CSS1 and CSS2 selectors are allowed plus quite a few CSS3 selectors.
Dustin Diaz names his top ten list, which includes Scott Andrew's addEvent(), Dean Edwards' cssQuery(). The cookie manipulation functions take the first three places, and the Prototype $() gets an honourable mention. Dustin also includes a JavaScript file containing all 10 favourite methods.