This being Friday, and after a week of exhausting back-to-back meetings where I pretty much spent all my flippancy and good humor, Mark Pilgrim's description of Monkey Do (his latest GreaseMonkey magnum opus) is just what the doctor ordered.
I personally find using GreaseMonkey to be a bit like ice-skating on chainsaws, but the description alone makes me want to update Firefox and have a go at it.
Update: It's kind of creepy, actually. I was puttering about YATWA looking for a TiddlyWiki plugin to add into the Grimoire, and it popped up a nice little rounded yellow floater with the message "it looks like you find this page useful - would you like to add it to your del.icio.us bookmarks?".