I recently discovered a variant of that type of social site that's a lot more down my alley, called GetGlue.
Just to toss out an easy comparison for those who are familiar with the sites, it's a little bit like a mash-up of Foursquare, Amazon, and LibraryThing. It has databases of lots of different kinds of media; books, video games, movies, tv shows, music, and just general topics. You can "like" or "favorite" all the stuff you like in those categories. GetGlue will then offer you recommendations based on stuff similar to the things you like, and it will also point you towards other users who like the same things so you can go see what stuff they recommend. You can leave reviews of things you like (or don't like) and respond to other people's reviews. And finally you can "check-in" to things whenever you're reading/watching/listening to them if you want. And for those of us with the acquisitive gamer streak you get awarded stickers (aka badges/trophies/whatever) based on the amount of all these activities you've participated in. I've currently got 18 stickers, including one for having liked at least 250 books so far (the first sticker started at 50 but there are multiple levels) one for making 25 check-ins in general, and one for making 5 check-ins to a particular item (in this case for checking in repeatedly while we were finishing season 2 of True Blood over the past couple days.)
Oh yeah, and if you're willing to install the browser plug-in (which is both somewhat intrusive and somewhat fun) you can like "like" items just by visiting affiliated sites, which includes places like Amazon, Wikipedia and Audible.
If anyone else is interested in trying it out (or already has an account =) I've got the same nick there, and you can take a look at my profile. Actually i suspect that anyone can take a look at it since i haven't set any privacy options. (I don't really care who knows what media i like, especially given that i'm using my LJ name =)
Although i should warn those people who care about collecting things, it seems that you get the "Lone Wolf" sticker for not having subscribed to any other people (aka friending) for at least a week. I got my sticker on friday and i've friended a couple people since then and it seems like once you've got the sticker you get to keep it. (And it doesn't matter if other people friend you during the first week, only if you friend other people.)