Hmm, I think its the first time that I feel Bruce a litle angry.

Anyway, I agree that pulsing a LED within its safe working area limits can be OK without resistor. Be careful of the Vf voltage. Usually on LEDs Vf is smaller than the one you may be used with other diodes.

About Melanies trick, it is of course doable 100%, with the assumption that LEDs are High Brightness to compensate for the Duty Cycle. Driving them for only a short time (1/30) at 10mA will reduce their brightness conciderably.

Ioannis