Milkdrop has become my favorite fullscreen Winamp visualization. Among Geiss's other plugins, I was also fond of G-force and Monkey, but their development wasn't as complete as Milkdrop. Anyway, I ...

I have fond memories of running TripeX on a voodoo2, but even today it looks incredibly slick - it's one of the only great truly 3D visualizations out there. There's Geiss 2, which is also quite old ...