I would say the success of a dating site depends on these two components:

a. Findability
b. Coolability

Of course neither of those are real words, but you get the point.

No matter how cool a site is, if nobody finds it then it's a bit like having a really awesome 1 800 number. Not a lot of people are going to dial that number by accident. You may say that a really cool site will naturally go viral, but in my opinion it takes a lot of daily visitors to get that ball rolling.

Here's see more one thing I would really love to see: Interactive Games! I know this was discussed many times before, but I really think that this could massively increase the "fun" quotient.