ThingM, are launching a new product, the blink(1). It looks like it has gone well through the kickstarter goal with $42,535 pledged at the time of writing. There are no details of the design yet, but I would bet the design is pretty similar to my Mail Notifier cube. At $45 shipped its a bit expensive – particularly as my design is less than £2, even buying the components individually.
ThingM have another LED controller project, the BlinkM, that might make a cheaper alternative. It could easily be converted to USB controlled as it uses the same microcontroller (ATTiny) as my Mail Notifier. The firmware I made should be compatible and you only need three components: two zener diodes and a USB connector.
Wire the zener diodes in series to connect from USB V+ to V+ on the BlinkM. Connect the i2c data pin that goes to pin 7 to D+ and the other one to D-. Finally, connect the PWR – on the Blink M to the USB ground pin.