Another way to turn off an LED is to remove power or simply remove it from the circuit. A hammer will also turn off an LED. If you omit the current limit resistor, it will soon shut off. I bet a microwave could do the job too. Perhaps this is the beginning of a "how many engineers does it take to turn off an LED" joke ;)

I checked out Chris Brook's page. It looks like he could benefit from either proofreading his webpage or taking a circuits class. There are tons of mistakes on it.

P Edson, if you want a more worthwhile "problem" to solve, I would recommend looking into ways of controlling external loads, especially inductive loads or high-current loads. I think this will yield more useful knowledge than "what is the most complicated way to switch an LED." Also look into ways to protect your micro I/Os and power supply from RF noise and over/undervoltage transients. None of this is secret knowledge, but it is essential for robust design.

- Lee