My favs:
Classaction - icon to drop any file on, and set up actions with. e.g. IFF file dropped opens a menu of view/edit (dpaint)/edit (image fx).
Tinymeter - button menus/submenus, kinda like a permanent start menu that sits anywhere on the screen, but can have more than one permanent 'category' button at any one time.
MultiCX - loads and loads of tweaks for various aspects of the WB GUI, built in screensaver, etc.
Edit: Pic illustrating Tinymeter, 'tis the entire column on the right of the screen.