I know Buffy! And DW, obvs, and also due South and White Collar. And sort of Inception (I saw it, but I never got into fandom). So basically I get exactly ONE HALF of each of these crossovers.

At this point, though I would basically take White Collar/ANYTHING. I just started watching season 2. I LOVE NEAL AND DIANA AND PETER AND OMG EVERYONE. (Except WHERE'S ELIZABETH?! And is it just me or did Lauren leave at the same time as Diana came back? WHAT, TV? CANNOT HAVE TWO BADASS WOMEN OF COLOR ON ONE SHOW, HUH?)