While window shopping one day, I saw a Hitachi Massager in a shop window. It's a vibrator that has twin head knobs side-by-side with a space in between. This immediately suggested some interesting possibilities, so I bought it. (It wasn't cheap-- about $80.)
The first time I used it, I knew it was a good decision. I'm fairly large-- about 6 3/4th inches when fully erect-- and my dick fits very nicely between the heads. The massager has two speeds, fast and slow, and I found that I prefer the slow speed. The build up to orgasm is very slow and gets more and more intense as you approach the point of no return. Finally, when you orgasm, it's incredibly powerful-- probably the most intense orgasms I've ever had.
I've also learned that it I put several thick rubberbands around the base of the massager heads, it pulls them even tighter together, grips the dick better and increases the sensation even more. Slowly jacking the vibrating massager up and down the dick shaft gives exquisite pleasure.
I've also used this on a couple of f**kbuddies and they rave about it. It's fun to watch a guy's faces as his pleasure builds and to hear him moan and grunt as he approaches and finally reaches his climax.
I hope some others will spend the money, get this devise, and write in with their own reviews.
A word of caution: If you get too rambunctious with it, it can rub you a bit raw. Be gentle! Take your time! It's worth the wait.