You guys are sweet. I was already on facebook before I started my photography business so I already had a bunch of friends from college and high school which I'm sure helped me.
What I did was create a fan page and send an invitation to all of my friends to join it.When they join it, it shows up on their personal page. Then friends of theirs see it and end up looking at my fan page and a lot of them have joined. I don't know a lot of the people that are friends on my fan page now. I then have my website and a little info listed under the work info on my personal page and I try to only add photos that are edited to keep my image up (HAHA)
Also, I only post a few photos from each event on my personal page (because then the mini-feed tells everyone in my network that I've added photos) and then I post a link to my fan page and I have an image that I add that says something like, "Want more? Check out our fan page and blog". Then I add the images to my fan page with a little note about the session. In the note I link to our blog and say something like, "For more images and to read more about...go to our blog". It's working really well so far.
I also try to keep my face in other people's faces. I keep up with my friends lives and try to leave messages on their walls. I update my status with exciting business news so they can know what I'm up to. I congratulate everyone I see that changes their status to "engaged".

I tag everyone I know in my images. Every image on my fan page and on my personal page has our website stamped on it so it's always free advertising.
and...last and most importantly...We tell everyone they can take ANY of the photos we have on facebook that they want and use them for their avatar or photo albums (we don't mind since our images are stamped). Then everyone they know sees the great photos and ends up going to our page. Most of our clients tell us they found us by seeing a friends picture that we took or a friend of a friend, etc., and then typed in our website address that was stamped on the image.
I also try to keep it fun and try not to send out too many blasts. I don't want to annoy my friends. I try to find a balance so they don't feel like they are being bombarded with business stuff. Hope that helps.
If you need help, let me know!
Ps...you can set your profile to allow people who are not your friends to see it. You can also give your fan page address to people just like any other link. You do have to be a little careful though, facebook has rules about how you publicize your fan page so make sure you read through them.