I'm more interested in the kind of stuff a person reads on the internet. If you read similar topics, we're going to have a lot of stuff to talk about, which is attractive to me. There are tons of people on dating sites who I am attracted to and are around my age. You need a filter, and similar interests are easier to express implicitly than writing a huge block of text about all the things you enjoy. That was the premise for a site I worked on (mostly dead for now), though it isn't targeted at dating.
Example profile: http://sitesincommon.com/users/niran