http://blendr.com/
I don't know what it costs (it wouldn't be much), but I read an article about this app called Blendr, that's owned by the owners of Grindr, a site you'd want to totally avoid, as it's for gay dudes.
It's apparently a hook-up app for straight people, that's masquerading as a dating site. I wouldn't be able to use this, as I don't currently have an iPad, iPhone, or a smartphone.
If I was going to meet a lady from this app, I'd refuse to, unless I first saw a full and clear face and body photo not just a face pic) and at least 3 or 4 pics.
With regards to this taking business away from adult dating sites, that for guys wanting to send messages out, are all pay based, I don't think those sites would be currently losing sleep over it.
Give it another 10 years and such apps probably will start heavily cutting into the profits of pay based adult dating sites that are full of fake female profiles and while someone could still have a fake profile on it, the GPS aspect of it, means a scammer in Africa can't con you like they can online. Women using this, are still going to go on looks and pics though.