I don’t remember where I found it, maybe /., but I found a really cool bookmarklet that will show you CSS information simply by mousing over an element. It’s quite cool.
Rather than putting it in here and maintaining a version, please check out the website for it.
VERY nice! I enjoyed it and see where this could be really helpful. Like when I see a page that I like and want to imitate (the sincerest form of flattery, after all).