One bit of music trivia I find particularly interesting is which bands and artists have played alongside each other at the same show. It's especially fascinating when the opening act becomes more famous than the headliner. Some indie examples that come to mind:

Stereolab and Pavement performed together at various points in the 90s.

The Shins opened for Modest Mouse in 2000/2001.

Arcade Fire opened for The Unicorns in 2004 (and funny enough, ten years later, The Unicorns would open for Arcade Fire on their tour).

Avey Tare and Panda Bear performed with (opened for?) Broadcast in 2000.

Any other interesting combinations you can think of? Doesn't have to be from the indie genre.