I was just watching Cage Rage 17 -- a very entertaining event with some great fighters -- and noticed there were no knees or kicks to the head on the ground, and no elbows to the head at all.
Everyone seems to think removing elbows from the UFC would make the sport "watered down" and lead to more boring stalling. That did not seem to be the case in Cage Rage, or in the IFL for that matter.
I'd love to see knees/kicks back in the UFC, because they can totally change the strategy in a fight (no more sloppy shoots or just sitting there on your knees since your opponent can't do anything), but aside from un-satisfying, fight-ending cuts, I've never seen elbows do anything that couldn't be done with punches.