1. Lose the shadow and shading on the forum areas then it will look much cleaner and not so murky. Plus it will make it line up and not look like the forum area are too wide for the background. It makes it look off kilter. Everything else for the most part look really good then you have this horrible looking shading/shadow
2. Make the logo not quite as tall. Really looks strange with the width of the forum. Its not proportionate.
3. Increase the padding on the style. Seems that it has been taken down really too much as there is no padding between the contents and the sides and letters are on the edge which for some people makes it very hard to read. It also looks sloppy. It will look much cleaner if you just increase the padding by about 10px.
4. Postbit looks great! I must commend you on that one.
Otherwise looks pretty good. I see you have done quite a bit of work with it.