So, another former (still technically alive but updated periannually at this point) site that I used to visit had I think 4 hosts. And they had contests to design headers and logos, which rotated from time to time but always featured the site name in the same font and size more or less. Color, texture, positive or negative space were all variables. And the banners were on a theme, but basically 10 or 15 would get thrown into a rotating banner bucket and when the homepage loaded you’d get a random one. Some came and went, often in batches on a theme or riff. There wasn’t really voting, as long as it wasn’t hurty or mean they’d probably use it for a while.