Shayne Terry -
"Strong" , and Marcus Rowland's
"California Cousin" are "Buffy the Vampire Slayer" crossovers.
Becky Bain -
"Timeless" is a "Beauty and The Beast" crossover.
I wrote
"Pie Isn\'t All That Easy" which is a "Pushing Daisies" crossover.
Wendy Richards'
"At Wit\'s End In The East End" is a "Doctor Who" crossover.
I know there are many more; these are just a few that popped into my head right now.
As Lynn said,
Marcus has a *lot* of crossovers (and they're all fun to read!)