The last batch of toothbrushes that I got (some subbrand of Reach) have an intriguing feature that I'd never seen before: little rubbery grooves on the back of the head meant for scraping your tongue afterward. They do an excellent job at cleaning up the tongue; my mouth feels cleaner after brushing now, and I'm pretty sure that this feature has also resulted in reduced morning breath. I'm very pleased.
There's only one drawback. Whenever I use the back of the toothbrush, I cough. Not just some little cough; an unpleasant, gagging cough with enough force to turn my eyes red. I've actually gotten to the point where just thinking about flipping the toothbrush over is enough to make me gag, and that's not an exaggeration.
At first I had hoped that I would simply get used to performing nightly toothbrush fellatio and the coughing would stop, but I'm annoyed that it's actually getting worse, because it actually is a very nice toothbrush feature.