It appears that the Melon Headband Alpha Android SDK is no longer available from Melon. See Melon Headband — Android Beta.
Below is a copy of the SDK that I received in April 2015. I successfully built and ran the AndroidMelonBasicSample application on my Motorola phone. It actually communicated with the Melon headband!
Melon was purchased by DAQRI in February 2015. They still maintain a Melon product page, but the Google+ Melon Headband - Android Users community (see update below) has been all but silent for over 6 months. That plus the website message "We're back in the lab crafting new things" is a good indication that Melon development is no longer active.
Download: AndroidMelonSDKSample.zip.
Update (4/6/16): The community has shut down:
