I know theres a hack to add a gif or gradient to the category tables etc. Actually I dont think the link is working(6.3), but is it hard to do manually? I was thinking it would be kind of cool to have this option.

Or even a template changer too, cuz I've heard that the color forums hack I think it is, is Hard on the server or something?

MyStyle was hard on the server. Colorforums is great on the server

and to do this it would be in public formum summary... or?

just searh for all instances of bgcolor="$vars_style{CategoryStripColor}" and add the background code there. (public_forum_summary.pl)