I have a Facebook fanpage up for my business (see below for link), and have gotten about 450 "likes" so far...most of them friends of people I know, the remainder of them are friends of friends. I'm on FB a lot, because I work from home as a graphic designer, and I've updated it a lot with different designs (I design t-shirts as my other, crafty, business). Have only been using it for a couple months, and have gotten a handful of sales from it, but no more there than from my website proper.
I've gotten feedback from a few people on the following:
1) Don't always post about "business"... that is, yeah, you want to sell your goods on FB, but make sure to not over-saturate it with "buy, buy, buy!"
2) Keep it fun... post some funny pics (tasteful, of course), videos, and links. Motivational quotes are good too. Or use the "Questions" feature in FB to start a poll, to ask your followers their opinion.
3) Keep your followers involved... like in #2, a Poll Question can be used, trivia questions, or just their opinion on a particular issue (usually best to relate it to your product). The more comments and likes you get from followers, the more of their friends will see it in the Newsfeed, and the more chance more of THEIR friends will come to your page to see what all the hubbub is about!
Good luck, hope this helped!