Trine does have really beautiful graphics, and does require a pretty good card to make it look great.

Age of Conan is hands down the most graphically demanding game for MMO's, there is almost an endless draw distance. Just cranking all the graphic settings to max with shadows enabled and staring all the way across Conall's Valley will put you in awe.

Metro 2033 for FPS, it has much higher requirements than Crysis.

I haven't played many racing games on the PC, but I think Dirt 2 and Burnout Paradise would be up there.