I agree with what has already been said...of course...
One harsh reality of starting a new social network is that people immediately compare you to big names like Orkut and MySpace and dozens more...its harsh, but its the truth. So to be successful, you need to think of ways that will set you apart from all the others.
Here's some advice,
1. the name and url of your site gives away a little bit of what its about, but as leo said, the
first thing any visitor should see is what they will get when they become a member.
2. and yes, putting up pictures of "good-looking" people on your home-page will get more people to register in hopes of meeting them; its stupid, but it works...just don't go too overboard, use normal good looking stock people, but not supermodels!
3. that ad looks scary on the first page, and it draws too much attention away from the main content; so you should move it somewhere else, or better yet, if you can remove it from the main page, so that new visitors are not intimidated by the ads!
In the end I'll just repeat what Joe just said...
QUOTE("Joe")
Your biggest referral is word of mouth, go and swap some links and post your website up on some directories such as Yahoo and Dmoz, try and get some search engines visiting your site and you should start seeing some visitors to your site.