Well, since we got used to programs filled with graphics and other stuff, we kinda forgot that actual code doesn't take so much room, and so many good old applications don't require that much room
Also, even though we're kinda going off topic here, some people are programming 3D demos where textures are generated through pure math procedures ... so you've got damn small demos that last several minutes and that's, well, most impressive oO ... if you want to judge by yourself, see there : http://farbrausch.de/
(All I have to say after this, is that those people that make benchmarks such as 3DMark and other similar stuff should take example on these guys )