Book Filtering

There are a lot of books out there: an overwhelming number. So even an avid reader must have some process of filtering which books to read. (This a problem with other media too, but I want to talk about books) I will sometimes pick up SF at the bookstore or the library that I've never heard of before, but anything of another genre must be vetted by some source.

My mother filters mainstream fiction for me, and I filter SF for her. (There are some authors we both know we like, but she buys the Kingslover and Chabon while buy the Le Guin and Beagle)

I also trade recommendations, and when geography permits, actual physical books with a variety of friends.

The internet is another source of book recommendations, through LJ mostly, but also as general place to read reviews.

I also sometimes read classics. When I was in high school I read classic SF, at the moment I've been reading some classic feminist SF. (Reading classics may be one of the reasons I always look at copyright dates. Does anyone else do that?)

Anyways I think that is all of my filtering methods. How do you filter your reading? What will you pick up as an unknown and what needs a solid rec before you'll touch it?