Admittedly POF isn't amazing but it's free.

When I was trawling it I had no problem having at least 2 new dates a week from decent girls.

I think it's always good to draw parallels with meeting a girl in the Street or in a nightclub. I've had more headcases who seem normal in clubs/out but then show their true colours than I have on POF, where you realize within 3 messages if it's going somewhere or they're a complete nutjob...