15 million members... Why not make it 15 million and one?

Ashley Madison is aimed at people who are bored in their current relationship. Cheating could be one way of describing it, unless you have an understanding partner... Honesty is very liberating (I speak from experience).

Friend Finder is free to join. The registration procedure is easy, and with 11 million members this site will deprive you of much sleep.

Fling is another site where you can find people who need their itches scratched... Interesting pictures here, but not recommended for Christians or Muslims.
If you would like to meet beautiful Russian women, then Anastasia is the site for you. I know some Russian women... Funny how cussing sounds the same in any language.
Yahoo Personals offers a wide variety of categories (i.e. beliefs, culture etc.) to help you find the perfect partner. I can't think of anything funny to say about this one.
Matchmaker is another very popular site which caters for multi-culture etc. categories. (Christian, Gay, Hispanic, Asian etc.)
Fed up dating guys with no money? All the guys on this site have been vetted... Only rich SOBs here. Just make sure he's not Scottish.
Want to practice your Spanish? No esperar Inglais? Want a free holiday in the sun? Es aqui! Vamoos!
Derived from the poplular and excellent UK reunite-with-old-school-bullies site, you are bound to find yourself a Brit here, if you don't mind living in wet and windy Blighty.