I suppose the ability to generate unbounded Facebook likes or Twitter followers is monetizable.
You could definitely contact your local firm of private investigators, insinuate that "I can access anyone's FB account," and make a tidy sum from doing just that.
Playing devil's advocate, admittedly, but there is still a very active market for quite petty-yet-nasty stuff, e.g. land developer wanting to access email accounts of local residents protesting against the plans.
Actually, you want weird? Thanks to my latest "seeking work" post on HN (and "Hacker" appearing in the page's title), I had someone ask me to hack the local authority computers responsible for registering peoples' deaths. This was, apparently, in order to give his funeral director company a leading edge.
Does Matasano never get cranks asking for stuff of a similar nature?
And you could just send them an email, carefully tailored to target them, with a link to your exploit site.