Beatseqr
Beatseqr is a personal project of mine that I’ve been developing after hours. It’s my finest work as an untrained enthusiast. 
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The main processor for the hardware is an arduino mega. When these boards came out a couple of months ago, I started to realize that there might be enough inputs to build some really interesting hardware controllers, and that turns out to be true. There’s so many pins on this board that I’m realizing that I’ve actually built in too many buttons and I need to go back to the drawing boards and figure out what else I can do to more effectively employ the entire microprocessor board.
The hardware talks via serial-over-usb to a Cocoa app that I’m creating called Roxor, which is a tangential brother to Rosco. Roxor’s sole purpose in life is to receive the serial data through the protocol I developed, and translates that data into Open Sound Control messages. One example for how this could be used is to connect it to Derek Scott’s beat sequencing Max/MSP patch “Steppa”. Steppa can take the OSC messages and loop them over time to create a sequence loop of MIDI messages and in turn can be picked up by any music app that accepts MIDI data, for instance, GarageBand, Logic, Logic Express, Reason, Live, and a whole lot more. Here’s an example of how Beatseqr can work:
Here’s an example of how you can adjust the swing value at a higher BPM to get an effective double-time effect:
More info will be posted soon. I’m still developing this project in my spare time.