1- Sensacell Music Sequencer
Developed by programmer Matthew Schlanger, the the custom music sequencer is a series of interactive LEDs on a screen that display graphics and play music according to where you interact with the screen. This was fascinating to me because of the beauty of the interface through the combination of music and visuals.

http://makerfaire.com/makers/sensacell-music-sequencer/
2- Hypnocube
This RGB LED cube was quite eye catching in the dark room. It pulsed with different colors, simulating 3D shapes. I’m used to seeing matrises of LED lights on 2D screens but this 3rd dimension was a new experience to me, bringing about endless possibilities of graphics generation.

http://makezine.com/2006/10/14/hypnocube-3d-led-kit/
3- Smomid
Inspired from the MIDI form and function, this DIY musical instrument created by Nick Demopoulos, is a guitar like devise that allows a performer to control melodies, harmonies, controlling beats, basslines, triggering percussion samples, manipulating audio files among other things. All these aspects can be controlled from the six strings and various buttons on the instrument. It was like a portable DJ set.

http://www.nickdemopoulos.com/smomid.html