How about Fray and BtVS? Too Buffy-ish?
dunno... have to check with the original poster to see exactly what they considor a 'crossover' to be... to me, writing a Crossover involves 2 or more distincively different universes that would not normally interact...
A fictional crossover is the placement of two or more otherwise discrete fictional characters and universes into the context of a single story creating one 'universe' from the two original fandom's used.
using that definition, i wouldn't classify a Buffy / Angel or Buffy / Fray fic to be a crossover, as Buffy, Angel and Fray already all exist in one universe, so it's not a crossover.
But again, you'll have to check with the original poster on this...
I do know if you check fanfic archives like Twisting The Hellmouth and Fanfiction.net, they don't consider crossing Buffy with Angel or Fray to be a valid crossover fic...
M