A browser version of Heretic rekindled my interest in DooM engine FPS games. I started reading DooM wiki on wikia, and read about Oblige. It's a random level generator for DooM, Heretic, Quake and Hexen*. It produces quite nice results - nothing comparable to handcrafted WADs, but very playable (if somewhat repetitive). DooM generator is especially polished right now.
For a sample, I recommend this DooM2 WAD I generated:http://www.sendspace.com/file/s15kjb
(generated for DooM2 and Doomsday Engine source port which I use, but probably compatible with other source ports)
One way to use the generator is to just have fun. But you can use it to speed up map creation: randomly generate some levels, take nicest of them, and modify by hand to make them more interesting and prettier. That would be the best of two worlds. I hear you have problems recruiting talented mappers, and/or ones you have are overworked. You should be interested. Oblige homepage is here: http://oblige.sourceforge.net/
By the way, what's your favourite level editor for DooM engine games ? Years ago I used Deu II, but perhaps there are newer, better tools ?
*Note that HeXen support seems to be currently disabled, but considering the generator is under active development (!) it shouldn't take long.