Can you even do that?
I would never, ever post anything other than cellphone snapshots into facebook, their photo UI seems to discourage it as a photograph sharing tool (snapshot sharing yes, but I don't know anybody that would ditch flickr for facebook).
Can you upload music to facebook? I don't...think so?
People are creating things, but facebook has no way of categorizing this stuff, so I don't think people are putting "valuable" things into it, because they know that they'll never be able to find them again.
The fact that greplin is looked at as such an amazingly exciting tool illustrates this, I think.