In rec.bicycles.tech Khoomei wrote:

What is the best internal shifting hub on these important points:
- reasonably lightweight compared to a road group
- reliable operation
- parts are available from the usual channels, not some guy working
out of his garage.
- has more than 3 speeds.

The 14-speed Rohloff Speedhub should satisfy all these requirements (and
many more), especially as you didn't specify any price limitations. See:

http://www.rohloff.de/?p=PRODUKTE/SPEEDHUB

It's about $800, available for example from Harris Cyclery.

-as