I discovered this one afternoon when I was keen to try something a bit different.
I realise that the equipment required isn't available to everyone but if you have any kind of massage chair available then give this a shot.
After reading stories here at solotouch, and looking at some pictures to get warmed up I set up my portable massage chair cover on the computer chair. By covering it with a towel, and then pulling it forward I could use the 'seat vibrate' function right on the underside of my shaft.
To increase the sensations I held my very hard cock down onto the vibrating pad.
Loads of pre cum oozed out, and the sensation was great but didn't feel like I was quite going to get there without some manual encouragement, however I found that by contracting my interior muscle (like stopping the stream when you pee)my cock started to twitch all on its own, I did this several times and it pushed me over the edge.
The best thing about this technique is that it leaves you hard, and ready for another beat.