The design is nice and clean.. but a bit bare. I think more colorful glossy web 2.0 styled icons would liven up your site's design.
I really like this elegant simple theme, and also like the idea of the top box (can we call it header?) kinda mozilla style with the menus...
I liked the blue color shades used in your forum. Also I am impressed with the font color of the buttons. I mean the brownish color. But what about the background page.Why have you kept it white. Try to play around wit some color for the background page.
The site design is nice and clean, but whats the main purpose and target group of your forum? From the first sight it looks like a webmasters forum, then a forum about general life and then towards fashion. Its okay to mix ideas but having loads of different topics is going to make it hard for you to attract the members you want. Good luck with the forum though. Keep it up!
Quite a nice design. Clean and easy to read which is important for a forum. One thing to nit pick at is the border going around the forums and topics. It's thicker on the top than the bottom. Think it would probably look better if the top and bottom of this border was the same width, or the other way and have the bottom border sightly bigger.