We have had enormous success with twitter...now its not only in our top 3 for traffic, but also sales. It's been so good for us we launched:
http://www.onhercam.com/twitter
http://www.sizzlingcamgirls.com/twitter
(anyone on twitter wanting hardlinks on those pages, hit me up).
You just have to be careful not to blatanly spam twitter and not get too nasty. They are somewhat tolerant of most things from my own experience.