Tongues are really versatile. Your creature could have a prehensile tongue (or tongues), or one that looks like the food of the thing your creature eats. For example, if your creature is enormous, its tongue could look like a hamburger to lure in dumb humans. ;-)
Sticky chameleon tongues are useful.
Venomous teeth are kind of obvious, to keep your meal from squirming.
Spitting poison or knock-out gas is fun too.
A light in the mouth might be nice to lure prey in a dark setting.
Instead of normal lungs that exhale and inhale, your critters could have additional organ that could quickly suck in a lot of air (or water) to pull the prey into the mouth.
And of course, no list like this would be complete without a Xenomorph's extra set of attack-jaws (from Alien).