4:3, i have a samsung 213t, and 95% of my gaming is wow which i run happily at 1600x1200, other games, if i can window mode them, ill play at lower resolutions, this display dosnt scale down all that well...
20" Widescreen monitor (Dell2005) running from a single BFG 6600 GT OC card. I'll use widescreen res if a game supports it (and if my card doesn't struggle with it). Desktop is at native res.
28" Widescreen Sony CRT -> Xbox 360/Xbox/GC/PS2 (no HD for me yet)
4:3 on a 19"CRT
Usually 1280 X 1024, since i couldn't find a 19" CRT that could do 1600 X1200 at a decant refresh rate and clairity. (yhea yhea, i could have gotten some used NEC, but i am talking about NEW CRTs).