Been thinking up ideas for a thread that's on "autopilot" like the top three threads on the site, no prompts, no clues, just walls. WallSpectrum would have been perfect, but it's already ongoing (though changing it now wouldn't be a terrible idea...) Anyway I finally settled on one that's pretty good.
Just post a wallpaper that 'POPS'! Or a wallpaper with something that pops. It could be of something brightly colored or a wallpaper with something that stands out against everything else in it.
Like: 
