On my recent electronic music show, Plugged In, I had the pleasure of having a friend guest DJ a set of old skool Electro.  He ending up bringing an dazzling tool to do this.  The open source hardware monome can mix and add effects.  Its extremely minimalist interface gives you no visual indication of what the buttons do, they just flash in amazing patterns.   Its beautiful to watch, especially when you turn the lights down.

The machine takes some musical know-how, but also a bit of DIY tinkering, as you buy the components and them assemble them yourself.  And it is fully customizable to be connected to your computer and programmed as you like.  As the website FAQ states, “by having separate light and button systems, the device can be reconfigured infinitely. new applications and uses are continually being invented.”