Here are some (fat) free jquery plugins.
Formidable: Custom forms with JQuery and CSS3
A plugin to customize your html / css forms using JQuery and CSS3 (it will, of course, fall back nicely in older browsers).
A small plugin to create a nice menu (drop down) using JQuery. It works as a css-only solution as well.
MicroGallery is a really, really small and simple JQuery plugin to create image galleries.
A tiny modal plugin for JQuery. Nothing more, nothing less.
Another small (css-file-less) JQuery plugin to create simple tabs.
MicroFilter - Filter by elements
Create filters and tags using this JQuery plugin.
Create Grids and Tables with this JQuery plugin which allows you to switch views (i.e. Table to Grid and Grid to Table, etc).