This one should work as well on the clitoris as it does anally for me, but I'm totally surprised I can't find any real mention of it on the internet.
First, find an Oral-B Pulsar(TM) electric toothbrush. If you look at it, it's just screaming to be inserted backwards into some tight little orifice besides the mouth - and it vibrates at just about the perfect speed - not too fast and not too slow, but damned fast enough, and it's covered with soft, finely ribbed rubber.
I lubricate the rubberized handle of the toothbrush well, and insert it in my anus just so that the buttons are still available, then turn it on and insert it the rest of the way up to the thumb rest, so the buttons are up inside me. I sit in a chair and lean back, holding the toothbrush in one hand while stroking my lubed-up cock with the other. A favorite method is to see how long I can go, with the intense vibrations tickling the sensitive skin of my anus, and the transferred vibrations clanging and reverberating off my prostate and the root of my shaft, while I'm stroking my lubed cock. Knowing that there's really no way to stop the vibration at this point without stopping everything and pulling the toothbrush out far enough to access the on-off buttons really turns me on too, but stopping becomes the furthest thing from my mind after just a couple of minutes, anyway.
I never time it, but as a guess I've held on for about 20 minutes or so before finally releasing in an incredible gush of cum in a giant, shuddering, gasping orgasm.
Sometimes I engage in this excellent and edifying technique solo with a little porn, other times my wife likes to just watch me do this. Still other times, she enjoys taking an active part in inserting and maneuvering the little Pulsar around my butt while we take turns slowly stroking my shaft.
I can only imagine what this little buzzer could do to a woman's clitoris...and what a discreet little toy, too! I give it two thumbs up...waaay up!