ive used a tongue vibrator before its ok, not the greatest they dont give off much vibration they are good for beginners who have never used a vibrator before. probably wont do much of anything for an experienced vibrator user.
I have one that's battery operated with pretty strong vibrations, but it's for pierced tongues. I got it at a local sex shop. So far it's the only one that's been halfway decent. The disposable slip on ones have all been a major bust for me. I find them uncomfortable to wear and light on vibration.