I'm involved with a project where we're doing some visualization using an arduino and a bunch (on the order of 20) LEDs. We're looking at using a Philips 4794 (a la http://arduino.cc/en/Tutorial/LEDDriver) to drive all the LEDs. The issue is power; it seems like powering the whole thing over USB isn't enough to drive all those LEDs plus the Arduino.
Anyone have any suggestions for a way to get something simple set up (perhaps using a DC wall adapter?) that would power not only the arduino, but all the LEDs as well?