So I have the links to all the stuff I use in one place:
- bgiframe
- BlockUI
- Cycle
- FCKEditor
- Flash
- form
- hoverIntent
- jQMinMax
- Lightbox (balupton edition)
- Metadata
- Multiple File Upload
- Validation
- Superfish
- Impromptu
- Thickbox
and of course, jQuery and jQuery UI.
Addendum (26 Nov):