Facebook is getting huge right now and a great source to find targeted traffic. You can use there advertising platform and target people based on keywords, interests and very targeted demographics, you can choose to do PPC or CPM.
You also can create fan pages, groups and events and target people that way also, having a event you can put people into a list then send them a message, its basically the same as sending out a email brodcast within your autoresponder. facebook has almost 500 million users now and more than enough traffic to go around and some for every single person on this site
I am just starting to see the power of facebook now too myself so am going to hit it up hard
hope this helps
cheers
-Chris