Infusion Systems makes interactive sensing systems for creative projects.  Their I-Cube product was highly inspirational for my own thesis project examining interactive controls for retail lighting, way back in 1999.  Here is a brief history:

I-CubeX arose out of a research project in 1995 directed by Axel Mulder, while he was doing his PhD on virtual musical instruments at the Department of Kinesiology, Simon Fraser University, to address the need for better tools for artists to create interactive art and for musicians to more easily create or modify musical instruments.

Hence the strange legacy of the MIDI interface scattered throughout their website (I’m sure there may be college kids today that are asking “MIDI?  What the heck is that?“).  But at least Infusion has upgraded to USB, BlueTooth and WiFi alternatives, and readily connects to systems like Max.  Infusion has accumulated great collection of example projects, called “Cube Culture“.

Although they now face competition from systems like Arduino, what continues to differeniate Infusion Systems is their amazing range of pre-assembled sensors.  If you are getting starting in interactivity, I would suggest checking out the demo videos they have of each sensor.  Here is the range of sensors they currently offer: