Interesting phrasing. Facebook is a very different animal than the other social online communities. I think the best documented case of successful high numbers of conversion from faceook is pandora. While it is far behind last.fm on the internet, on facebook it is king. Other than the facebook platform, I think the flyers are useless and sponsored groups are too expensive. Myspace is much easier to get traffic from. However, thusands of spammers already know this so it makes it harder for newbies. The best social mediums for traffic IMHO would be digg.com and StumbleUpon. However it becoming increasely difficult to make it to the front page. and as StumbleUpon becomes more popular it will make it less likly your site will be stumbled.
An effective way might be to create a facebook application. Although this doesnt necessarily guarantee traffic to your website.
then the next question is, how to come up with good ideas for viral money making facebook apps, looking at other apps gives some inspiration, but what are the attribs of a solid cashcow fb app