What are you looking for?
A whole new set of forums or just a template?
If its a new set of forums www.simplemachines.org
has a tremendously functional and great forum client that is completly free. Its by far one fo the more powerful PHP packages availible. Its what I use on the Corruption Feed
forums. I just used a userbased created graphical template and a set width feature to match the 750px width of the site.