oooohh look what I found -
These are all US based, and recruit in the US only, I have addresses for similar services run in the UK, Europe, Australia, South America, Canada etc etc... if anyone wants some, tell me what kind of work and I'll pass on the link.
Now, what are they? Well, they're a database where you can sign up, leave your CV details to be viewed by companies that are registered with the site, and view jobs that companies have left and apply for them. I've seen a ton of jobs advertised on one of the UK boards that I've not seen advertised anywhere else, and I know a few people that have gotton jobs through the UK versions of these sites fairly quickly.
So it might be worth signing up!