Somebody around here once suggested using hoards of modified Loup Garou as a "Dawn of the Dead/28 Days Later" type zombies (yes, I know they weren't "dead" in 28 Days Later) and make the disease contagiuos (sp?). I liked the idea because the enhanced sats for the Loup Garous make them fast and nasty as opposed to the sluggish nature of zombies. They also provide a new, non-Goul, "undead" monster. Just don't call them Loup Garou.
Run any module with Bugs. Missing Blood and Queen Euphoria are my favs.
Another good trick is using a Protaen to act like the alien in "The Thing." It will help if you see your players outside of your game. You could try to prime them by having a movie night. Just make sure you pick the movie...
If that fails, do what Shanshu said. Roll a bunch of dice behind your screen and chuckle to yourself. Then radomly ask a player what his/her Willpower (or Perception, or Reaction, or Quickness, or etc.). Then shake your head, chuckle, and pretend to jot something down on a notepad.
Rinse, lather, repeat as neccessary.
[Horrors? Bah. Go Humans!]