My skill mainstays have been Promethean and Blood Magic.  I've gotten accustomed to laying waste to zoos in a matter of minutes with Obvious Fireball.  I've been wanting to try out other builds but I can't find any other skills that take zoos down as well as Promethean.  Funneling mobs into a choke point and whacking away at them one at a time is fairly easy but boy does it take a long time, especially when the mob count gets over 100.   So what are some other good area effect/zoo clearing skills like Obvious Fireball?

:( I was going to suggest Obvious Fireball.
 
Try Golemancy or any kind of ranged weaponry. Also, it's good to have a teleportation spell in case things get a bit too hectic.
 
But anyway, Obvious Fireball is the obvious choice...

Bolts that deal AoE damage (like acid bolts) are pretty good, as is the Bolt of Mass Destruction (but careful with that because it'll knock out the walls as well). Summoning multiple pets seems to help out quite a bit too.

Oh, I almost forgot, Holy hand grenade :3

yeah, I was gonna say bolt of mass destruction as well. I didn't even know what it did, but when I came across my first zoo I just started firing all my high level bolts through the door.

I've been trying to do a melee/tank guy with a good mace and self-made armor.  I guess my only option is to start shooting those bolts.  I usually sell them off when I see a super high level item I want at a shop.

@LiQuid3600: No No No No. If you are powerful enough, you can Zoos pretty damn quickly with strategic use of health potions and viking magic (if you chose it).

Failing that...bombs!

I had a powerful melee character. His tactic was standing in a 1 thine wide area and let them come to the slaughter :D 
 
P.S. Just killed Dredmor 3 minutes ago.

None of my characters have really had any form of AoE, so I've had to find that choke point nd let them funnel through. My current martial artist/monk build has crazy dodge/counter rates, but still can't really effectively take out more than a guy at a time.

I always go with a fighter, so my strategy is to find/buy "Squid Bolts" and use them only during monster zoos. A Squid Bolt will usually kill 20 monsters, cleaning a bit the entrance and allowing you to devise a strategy for quickly taking out the remaining of the reatures, that are uaully weaken by the bolt.

I actually think that the Promethean Magic skill is OP. I used it for my first builds it worked wonders. With my current build I Usually use some kind of granades or bolts or wands i have, or funnel them. But I have a much harder time.

I just killed dredmor today :), used a duel wield staff build with fleshsmithing. the final talent in fleshsmithing destroys zoo's very nicly even on level 10.