Please note that this review is of the main page only. I did not venture further into your site.
Design
1.) Flash animation: for some reason this part look kind of bland or faded to me. This is merely a color issue for me though and should be an easy fix.
2.) I would suggest using a larger font size for your main content area. Which on the main page would be your "Welcome to..." content box.
3.) In the "Welcome to..." introduction text, why are the words "join now" not linked to your sign up page?
4.) The text in the login box is kind of hard to read. In particular I mean the "Register now" link and the "Sign in" on the button.
5.) The white text in the "Featured brags" and "Most popular brags" sections is hard to read on the chosen background colors.
6.) The links under "What people are bragging about" are in desperate need of structuring. As is they hurt my eyes and as in such, I don't even want to go threw them.
Those are the most important issues that I would address, as far as design/layout is concerned.
Concept
I would like to start out with a simple question...
Why should I as a user consider joining your community/social network over another? What sets your apart?
Your main page is your chance to sell a user on your idea/product. For me, it didn't really do that, as the entire page focuses on only one aspect of your community site. And that aspect is one that is rather self centered.
I haven't come across any social networks based on the same subject matter and find it to be a an interesting idea. However, I would try to perhaps spin it a bit differently and possibly promote the community aspect of the site a bit more.
That's just my .02 cents though, others might feel differently.
Anyways, best of luck building your community!
