!classes (drag to Links-bar)

Clicking this bookmarklet shows a list of all class="..." params found in the current page, and indicates how often each class is used. Handy when cleaning stylesheets of unused .class definitions.

Update: fixed it to work in IE5 as well... ;-)

Update:
Here's a version that lists the classes in a new blank window, for easy selecting/copying to clipboard:
!classes in new win