I'd have to say "mustlovesex.com" is by far the best domain name there.
Tasteful, memorable, usable brand.
Mine are:
Flirst.com
(cross between first and flirt. probably better for virginal dating, not adult dating)
3cupids.com - cupid for fun, cupid for dating, cupid for sex
dancefloor24.com
MysteryDater.com (could make a fun online dating game)
Comments anyone?