You know I've noticed something.
Half the people here that use Facebook to advertise go for the same tired old cashchow shit, without bothering to do some research into what Facebook admin or users actually respond to... It's old news that Facebook don't allow diet, gambling, adult, download or mobile stuff, unless you happen to cloak it cleverly enough or modify where it goes to after it's approved *coughcough*
HOWEVER, all the social networks allow you to micro target your audience to an amazing degree! And you know what? If you really know your audience, you cna get some great conversions on stuff that's a little bit out there.
From a single nerd specific keyword (as in that's the ONLY keyword in the whole campaign set of 6 ads), I'm pulling about ~$100 a week from a $35 spend.
I'm about to start asking my missus' dad, who's a massive jock, for some good keywords for his interests in cycling (as it turns out, he spent $2,500 on a bike frame, and there are 12% commissions on a few cycling stores in CJ)
So know your audience, target micro-specific interests, and you'll actually be able to make a multitude of smaller, but easily approved revenue streams.