Mister Starshine was not satisfied with commercially available music keyboards. So he built his own keyboard using the Jankó layout with hexagonal polycarbonate keys.

Here's a video of the keyboard in action:

The Jankó keyboard design has 2 great advantages:

1. All scales are played with the same fingering, no matter what key it is played in.
2. It is easier for one hand to play greater intervals.

Although it was invented in the late 1800s, the Jankó keyboard never caught on, except among a few enthusiasts. You can try the playing it for yourself with this Jankó keyboard Flash app.

Actually, this is just one of many types of alternate keyboard layouts created to make playing music easier. But with limited commercial availability, it looks like the best bet may be to make your own keyboard.