WordPress Themes that use jQuery
Recommended by @JtGreen
Free WordPress Plug-ins that use jQuery
WP Wall is a “Wall” widget that appears in your blog’s side bar. Readers can add a quick comment about the blog as a whole, and the comment will appear in the sidebar immediately (without reloading the page).
Insights brings a powerful new way to write your blog posts. It increases productivity and at the same time the appeal of your posts. With Insights you can very quickly Search your blog for posts, edit them or insert links to them into the current post, Insert Flickr Images, Insert Youtube videos, Search and link to Wikipedia, Search Google, Search News, Google Blog Search, Insert a Google Map and more.
µAudio is a slim (450 Bytes!), fast plugin to create a flash mp3 player when mp3 links are clicked. In order to reduce clutter and file transfer, the links are unmodified until they are clicked, at which point a div with the player is faded in after the link. A second click on the link fades the player back out.
The smallest Lightbox-like script available for the jQuery library, if you have a thumbnail you can click it and the full image version pops up.