Went to the Web 2.0 Awards List and had a look at quite a few of these sites - most seem very US-oriented, and a couple were no longer around (one link took me off to some US Insurance company's site) - so you'd want to be a bit careful about what you end up uploading to some of these sites, especially those that offer internet storage and online sharing options for your documents (in other words, back them up if you need to keep them). (And don't use them to store confidential work-related stuff - that should be a no-brainer).
A few are sites we've probably all seen before, but some were completely new. I can't see a direct work-related use for many of them - they fit into the 'fun but use them at home' category - but I would use the mapping tools for creating local history content. Wayfaring looked nice, and so did Community Walks, (though even with broadband they are slow to load and to navigate).
I also set up an account on eSnips - one of those Facebook-y type sites - though it's slightly worrying how much personal info you are invited to post there. Good to have an alternative online identity. Not sure how much I'll use it, but we'll see.