Duke 3D
Redneck Rampage (I dunno why, I like it. Maybe I like hearing rednecks' funny voices

Also, it was highly detailed for it's time.)
Albion (Still my most beloved RPG, first I ever played. Nothing beats beautiful 256 colors)
Daggerfall (Recently released for free download by Bethesda)
Of course, I always go back and re-live child memories every now and then with a genesis Sonic game.