I would like the idea of a "Halloween" update to MassiveMagic. Maybe all the bats and witches (can people summon them?) players spawn get an orange name "Halloween (mob)".
As for events, I would love to see more of the PVE things, though maybe slightly fine tuned to be less of a lag factory. I crash 4 times on average in those things lol.
For RP stuff. Vampires and Ghosts. Ghosts are seemingly canon now, having some stuff going on with them like the current haunted ithanian house stuff would be awesome.