Starrlabs - Mini Z
The Mini Z is a very powerful and useful midi controller that helps me program midi the same way I would play a touchguitar. One can program it with great flexibility and depth. I have both my Double 4ths tuning and 5ths/4th tuning programmed in. It's a great performance tool and practice instrument. I take it with me on trips, it fits in the overhead bin of airplanes!
C-Thru Music - Axis 64 and Axis 48
I discovered the Axis 64 while doing research on alternative midi controllers. I am not fond of the piano keyboard setup but enjoy playing piano sounds. The Axis 64 is a wonderful way to bring a composer or instrumentalist to new places harmonically due to the setup of the instrument.
You Rock Guitar
The YRG was a bit of shot in the dark because it looked like a toy but it was so cheap that I tried it. To my surprise it's close to being a serious instrument. Once they program the ability to trigger two notes on one "string" it will compete with the more expensive instruments.
Zendrum
I'm not a drummer but I purchased the Zendrum hoping to do drum programming. It has a lot of flexibility and a light touch so it's very playable.