Blogs can work providing you can write something worth reading. I've gone through a bit of a slump recently, but I feel it's a way to provide a more rounded view of your capabilities and personality, so for instance I got 2 wedding bookings partly because people liked my interest in playing the war photographer!
As for Facebook, I think that's currently the one to go for. For my personal self I don't like it. I hate the sweetly-innocent way it asks "find your friends" when it is really intending to mine your computer's address book, and I don't like how its goal is to make them money by exploiting your personal data and social connections. And even though I have almost everything marked private, in real life my friends either do or don't get to know my other friends because I introduce them, and they don't see conversations between us - so I don't like that happening because I've effectively dumped my address book onto Facebook. Professionally however, I think it is different and putting the business on Facebook can help develop an ongoing relationship with your clients. For instance Lakeland Photographic Holidays
use it to keep in touch with people who have stayed there and to show current and planned activities, and it's clearly separated from their own personal Facebook activities. They haven't any interest in updating their own web site themselves, so they can update Facebook easily and reach more clients than in by maintaining a blog. So I wouldn't dismiss it. Its popularity doesn't show many signs of diminishing.