Alright, how does this sound?

If the player triggers a pressure plate, spring-loaded launching mechanisms lining the walls and ceiling fling 2d4 Dire Weasels which do 1d4 gnawing damage each, and the target is Slowed and suffers 1d4+1 Ongoing Damage. Save Ends Both. Increase dice size at DM's discresion and/or sadism.

Also related trap Matt may know about - Bucket o' Axes, & Tingle Napalm.

Bucket o' Axes is, naturally, a bucket of axes. Set over a partially closed door, it does Level Equivalent damage to whoever walks through the door first, unless disarmed by a Thievery check. Tingle Napalm wreaths the target in fire, but rather than burning them, it gives them that annoying tingle sensation you get when your arm falls asleep. Only over their whole body.


Y'know, I actually have an idea for how to impliment these traps in my upcoming game... But I don't want to derail the thread any further.