Purple and grey...very interesting. It's quite new and unique, for me anyways, so good job there. It's always daring when you try out new colors, and you did a great job on it. Looking around at your forums it's sort of hard to look for anything to give you suggestions on, which of course is a good thing.
I don't like the menu buttons though, actually it's the border around the menu buttons and the black line which seperates the menu buttons. It just doesn't seem to "blend" in well with the whole menu bar. I also think you could get rid of that footer/base image on each category with your forum name on it. It's sort of annoying seeing it so many times when scrolling around, a simple base image would be fine. And instead you could change your header image's font to the one you use in the base image.