Has was mentioned. The drop bar ends from Origin 8 are pretty good also. But I've also tried the Ergon bar ends with the comfort grips and also give them a thumbs up.

http://www.amazon.com/Origin-Bicycle...6826309&sr=8-3

You can either keep the grips on your mountain bike or remove them and take bar tape and wrap around the Origin 8 bar ends and the handlebar. This set up also allows you to keep your brakes where they are now.