They ask tons of questions, so they have interesting compatability rankings to see if the girl is a "friend" or "enemy." It's pretty innovative so the site is worth checking out.
Free Dating Probably one of the best free online dating guides on the Internet that reviews and ranks all of the top dating rooms.
It's broken down by city and who you're looking for, and the link above is to the Los Angeles casual encounters page of women looking for men.
Many of the posts are bogus, and they do a good job of fladding them, but there are definitely real people looking to hook up posting on these sites, so if you're willing to spend the time browsing, then have at it.
Fortunately, there are now plenty of sites that are completely free.