For me, I liked the nVidia Logo which can be enabled in the older geforce drivers for games and demos running in D3D mode. Too bad this has been omitted completely. It's trivial stuff, but interesting and quite nice to look at. Something like, reminding you that you're running the game using a cutting edge technology graphics (even if it's not). 😁

The option to select it:

Few images from Escape from Monkey Island : (Notice the logo at the bottom right corner)

And from System Shock 2 :

I'm not exactly sure at which version they stopped providing this option, but I believe upto the last of 40's (4x.xx) series of drivers (for both Win9x and 2k/xp versions) . Haven't tried the 5x.xx series but the 6x.xx drivers don't have this option anymore.

I always wondered if anyone can come up with similar logos for ATI and 3dfx. I think it'll be cool seeing the above games with the 3dfx logo.