E-stim is short for Electrical STIMmulation and has been gaining in popularity in the past couple of years.  That's not really too surprising given the amount of nerves in your private parts compared to other parts of your body.  With the help of a properly tuned E-Stim device, you can tingle all of these nerves into orgasmic ecstasy.

These work solo as well as for couples, and for each there is a whole world of things you can do and try that may get you to a fast and heavy climax, or steadily maintain a slowly spreading tingling sensation that will keep you happy for hours and hours. Whichever way you like it.