New bookmarklet: counters
(drag to Links-bar or right-click to Add to Favorites)
Tested in IE6 and Firefox. For every mouseclick, a small , ,  incrementing counter will appear. Handy if you want to easily count the number of times something occurs on a page, such as the number of films you've seen of a specific IMDb actor/director (which prompted this idea in my case).
Quick hack to allow custom text, rather than incrementing count: notes