To me they're just another tool. On Facebook I'll post a link to one of my new websites and the site statistics for that site will show a jump in traffic at that day/time. I also have a client that wanted to be able to add updates and current news to his site himself. He uses Twitter and I had him get a Facebook account. I then made a page the shows his Twitter and Facebook feeds in placeholders. He can say what he wants on those and they display automatically on his site without intervention from me. On the downside, there are people that ask questions on Facebook only to generate discussion/traffic without really caring what people have to say. Social networking isn't going away, might as well take advantage of it.

Jim