Check out the TritiLED project. It's an inspiring feat of over-engineering. Among other things, it prompted Ted to build an automated LED brightness-measurement rig to calculate the optimal current to drive the LEDs.
Now here's my take using whatever was on hand: an "ultra" brightness amber LED, a 0.15 mH low resistance inductor, a small logic MOSFET, an ATtiny45, and a capacitor on the power rail.
Same topology as Ted's design: the FET pulls the inductor down to ground, and the LED is wired across it, where you'd normally put a flyback diode.
I'm pulsing on for around 1 microsecond, on-off with no delay for a 1 MHz AVR. The pulse rate is once every ~16 milliseconds, because that's the default value for the watchdog timer.
For details, see the code (in a Gist) or read on.