some models of blackberry have a fantastic multi colour led which allows you to specify any rgb value as the colour, here's a little app that cycles through the palette, quite impressive the first time you see it. tested on a 8700 and 7100, not sure what other models have polychromatic leds:
sundaracommunications.net/downloads/blackberry/led.zip
and the relevant code snippets:
LED.isPolychromatic()
LED.setConfiguration(1000,1000,LED.BRIGHTNESS_100) ;
LED.setColorConfiguration(1000, 1000, 0x007f0000);
LED.setState(LED.STATE_BLINKING);