Share 'Which Social Bookmarking Sites do you use?'

I guess this post is really a two parter. I've talked to some of you about trying to organize the Higher Ed Web community in a Social Bookmarking manner and am attempting to take a Stab using Mixx. I've created a group today that is for submitting Social Bookmarks worthy to be shared with the Higher Education Community. If this is something that your interested in then head on over and join the H…