The whole lot (including the crap ones) are HERE - but please try to ignore the less inspired ones!
The "pure" Buffyverse ones (minus the crap ones) are HERE
The shorter Buffyverse crossovers (minus the crap ones) are HERE
The Hellblazer / Angel crossover is HERE
Two Non-BtVS Harry Potter crossovers are HERE and HERE
The Stargate multiple crossover is HERE
Reposted with broken link fixed