I posted this on http://www.rpg.net/ in response to someone asking how to make zombies more original. This might not be original, but it sounds like fun.
'I'm going to try a Shaun of the Dead/Reaper approach. You know the quote 'When there is no more room in Hell, the dead shall walk the Earth'? Well, I don't think I've actually seen anyone do that.
Great fissures could open up, some could swallow whole cities, and the soulless shuffling denizens of Hell start to walk the land and kill all those still living in a fit of jealous pique. The zombie apocalypse begins.
Satan (who looks like Joe Pesci) is a little peeved at the mass breakout, then enrols the help of the PCs (who's characters are/were losers in real life) to get the dead back into Hell. They can do this in the only way available to them - remove the head or destroy the brain! Watch as the players queue up to play characters wielding cricket bats and wearing white shirts. With a bit of red on them.
A zombie brain-smashing adventure story in a Terminator-esque apocalyptic setting with a twist of black humour. Where can you go wrong?
Another idea I had was a properly dead zombie - no growling, moaning or grunting. They're dead, so technically the lungs don't work anymore so the vocal chords are shot. The skin is tight and pulled back, like it's shrunk on the body, so the bones are prominent and the fingerbones are through the skin like claws. They move as a normal human being, running and jumping and climbing, the face is totally expressionless and they'll stop at at nothing to kill you. In absolute silence. So, you can fight them off, hide, or wait until they rot away like a good dead body should. Oh, and they outnumber you thousands to one. Pisser.'