Any excuse to cram in a reference or homage to pop culture, or, even better, previous RP's I've been in is gold to me. Doesn't matter if people don't get the reference, although of course it's better if they do.

I also really enjoyed the excuse to play ridiculously over the top hammy characters in murder mysteries I was running. Three dimensional, thought-out characters are lovely, but sometimes you gotta just gobble up that scenery. Bonus points for Wolf Manor for the time that I co-wrote an accidentally and ridiculously homoerotic scene and Sol the German megalomaniac, Felix, his French dogsbody, and Jonas, his discretely gay American houseguest could never look each other in the eyes again.

Honourable mention also goes to Wolf Manor, where there was obviously something secret in the manor's lake. OoC speculation was rife, up to and including the possibility of aquatic werewolves.