Meta Data on the mind

I see lot’s of sites who’s head tags are stuffed full of meta tags and link tags, yet I rarely make use of such data on the sites I build. So I’m interest In what meta data you put into your sites and why. Andy Budd::Blogography: Meta Data: What do you use

Looks like GeoURL and Dublin Core are the two leading favourites. Probably still lots of room for apps that do interesting stuff with this information.