Luxeon Logic, brightness control for LED torches

The small super-bright Luxeon LEDs from Philips are suitable for many applications, including small but handy (that is, bright) pocket torches. However, you don't always need maximum brightness, so it would be nice to have a simple brightness control. The circuit described here is baed on an ATtiny microcontroller to enable convenient one-button operation. Three brightness levels can be selected by pressing the button one to three times in succession.