From around 1998-2000, Missy Eliott, Timbaland, Aaliyah and Ginuwine, self-dubbed the "Super Friends", were everywhere. Aaliyah was America's darling, Ginuwine was the self-proclaimed Bachelor and Timbaland & Missy put the "super" in Super Friends. The unique style and visuals were ahead of their time and can be credited for a few trends today (see: Drake). Always in each other's videos, here's some memorable cameos.
Missy, Timbaland & Magoo, and Aaliyah - "Up Jumps Da Boogie" (Why isn't this on Spotify??)
Aaliyah - "Are You That Somebody"
Timbaland & Magoo - "Luv 2 Luv Ya"
Aaliyah - If Your Girl Only Knew
Ginuwine - "I'll Do Anything/I'm Sorry"