nilsjohan,
I think that the black and grey background is good, and so is the yellow/gold font. Because it keeps with the theme of that "piano forum" tittle on the top of the page. I suppose you could have a couple of colour schemes just for a change for some people, it'll probably get a bit dull in time. When you have these different colour schemes, you can let members choose their own preferred scheme, from a options folders in profile. Also avatars could be fun, just a little picture under screen names, not too big, perhaps 48 by 46 or something... it'll probably take a little longer to load each page, but could be fresh. But i'm not too fussy about the layout of the forums =)