http://www.mw32.com/ is the best (sorry Matt yours got to be too busy for me and you weren't really interested in suggestions.....which is fine)
plus the guy at monkeywrench does all Michigan area teams, like the Griffins.
To each his own, but I don't recall seeing suggestions other than different screen resolution requests. It's not difficult to throw a red tint on a wood texture and just slap logos/times/tv on and call it a wallpaper. I prefer add more detail, additional time, etc., into these as I have done for well over a decade. That's all.
As for everyone else: As long as they're the 16:10 and 16:9 aspect ratio re-sizing them is fine. What I may end up doing is the high-resolution version of each ratio, then allow your PCs/Macs to scale them down to fit.