Spokeo could easily be renamed as 'Spookio' because it's one of those 'omg' resources. What it does is gathers details on all your friends from your various networks into one easy to find place. I started by adding my Gmail details. It then went off and found a dozen or so contacts which it then displayed for me. I dipped in and looked at the information on one contact. This included:
His Amazon wishlist (2 items, including the Cluetrain manifesto, in case he wants to identify himself!)
His Flickr account
MySpace details (just a photograph)
hi5 profile details
Multiply site photographs
Other accounts for different people included digg, Upcoming, Picasa accounts, LinkedIn and a bunch of others besides. And, more than that, it was able to work out who friends are even when they're using different names. One gmail contact that I have goes by 4 different names, depending on if she's on digg, Flickr, MySpace or Twitter. All in all, it was a real eyeopener and not a little spooky, as I say. I didn't much like it, because it felt like I had been invited into a friends house and was poking around in their drawers while they went to make tea. Not something I'll be using on a regular basis, but useful to know it's there I guess.