Some of them can still be found if you look around on Google. Unfortunately, they haven't aged well -- their wallpapers are mostly for 4:3 monitors and low resolutions, the textures are for low-res screens etc..
box-look.org has a few more recent ones.
Yeah, you're right. Back in 2001-2002 people would walk by my computer screen and be impressed, ask, "What OS is that??" Now the other OSes have caught up in appearance.