Hmm....ARRRRRRRRRRRGH's list is pretty bad, but I think I can do a bit worse with the Chaos daemons. The Epidemus + Nurgling combo is a little too potentially effective:
Herald of Nurgle  x3
5 Daemonettes  x2
6 Furies 
Epidemus and the heralds don't really add anything, and can only attach to each other. The rest of the army is 16 models, 10 of which have toughness 3 and only a 5+ save.
I agree with the consensus that vehicles of any type, and large quantities of bodies (even if they're guardsmen or grots) is more effective than some give them credit for. Now here's a crappy Ork army:
Warboss w/powerfist, attack squig  x2
3 Nobz w/3 powerfists and 3 ammo runts  x2
Yeah, they're great in close combat, but they all have 6+ armor saves, move slowly, and you only have 8 models on the table.