Hahah, Marphy Black (aka MarphitimusBlackimus) has a screenshot on the ZM forums of Poundemonium, I'll go get it.
edit
I hear you, man. This one time I was using the Poundamonium mutator when all of a sudden Crawlers started spawning. I mean, what kinda bullstuff is that? Is the game intentionally trying to ruin the delicate balance set by Poundamonium? >:(

And don't forget this little beauty from him, I only left in the best screenshot out of 4.
Thi is using the same mutator shwon by him in the second video Scorpion posted.
While playing through Suicidal difficulty with the Poundamonium! mutator activated is fun, I'm sure everyone here has seen it's quite the cakewalk. Hence, I've decided create my own mutator, something I've never tried before. Here are some screens from the first exciting playtest:
-snip-

-snip-
-textsnip-
-snip-
He plays the UT2k4 mod though, not the retail Source version