I set up an account there a while back---
http://monsterpappa.deviantart.com/
It's easy to use, but honestly I've yet to find any real benefit to signing up. I'm not entirely convinced that it's a great venue for reaching out to potential clientel... I've gotten several thousand pageviews and a handful of commission inquiries, but nothing that amounted to much more than a fellow artist wanting a maquette sculpted of one of his/her creations (for pocket change of course). To be honest, I only log in once every couple months, just to make sure I haven't missed any interesting private messages. Of course, if I didn't already have a personal website to serve as an online 'portfolio', I would probably view DA as being invaluable.
It's a good place to meet other like-minded artists though, if that's what you're looking for. Just be prepared to sift through thousands of "how did you make that?" and "your stuff is teh awesome!" comments on a weekly basis.