Couchsurfing does allow you to set your search parameters, so you can choose things like age, language, gender, etc. of the person/people that you're looking to host or be hosted by.

It def. seems more niched for the backpacker crowd, plenty of non-backpackers there as well. I've had really great experiences with it. It's also a great resource for "local" info. on local favaroite places to eat, see, etc.

It's also not only for those looking for a free crib...you can set it to search for/host people just for meeting up for coffee or a drink, etc. It's clear that it's NOT a dating service, and it offers ways to verify & vouch for the people being considered.