Del.icio.us has a new (or at least, new to me) URL history tool that tell you who's posted what about the site/page in the past and what they said about it. The history for SEOmoz is bland, but some others are more interesting (WARNING: The service is very slow):

You can use this service as a sort of look into what's been popular at a URL in the past, how it's heated up or cooled down in the eyes of the social taggers and even as a comment or reputation system.

What do the deliciousers think of your sites? Post, too, if you find anything particularly compelling for any big sites. I'm thinking there's some fun dirt to be had if you dig deep enough.