I made some traps as well. Here's a short list of what is in my trap zoo right now. Keep in mind these were intended for the player and NOT explicitly for zombies.
-Mounted shotgun (works with a pressure plate, uses trigger_hurt and trigger_push to simulate shotgun blasts on the player)
-Flamethrower (much like the shotgun, but is more scripted...env_fire entities placed everywhere and then the fire spreads, dealing damage over time instead of an instant damage like the shotgun)
-Grenade cluster (works with a tripwire, spawns prop_physics grenades with red blinking sprites and chirp noises)
-Swinging object (works with a tripwire or if the rope is damaged, you could use many different objects and swing angles to simulate variety in your traps...ie meat hook, rebar sticking out of concrete, steel beams, dead bodies (for scaring), poison-tip arrowheads (simulated poisoning ala poison headcrab))
-Combine orb (kind of like a grenade, it sits in the middle of a room...and once activated, a Combine orb is set loose and bounces all over the room...one could add more orbs for much more danger)
-Electric floor (Pools of water get electrified, slowly shocking everything to death)
-Lasers (env_lasers move up and down corridor ala Resident Evil)
Things I still want to make...
-Collapsing structure (I want the roof and walls to cave in without totally killing the player...more like a tumbling of debris that is somewhat survivable and maybe avoidable, so it doesn't feel like a cheap death)
-Pitfall (roof caves in and player lands in acid or spikes...again, I dont want this to end up being a cheap BS death)
-A few more that I have typed up at home...
"Day breaks, but decay soon follows."
- Ava WinonaCurrently developing in radio silence... 99 BoltsHere's another project of mine... Assault on OverwatchAre you new to Source SDK? VDC