Several Olympus camera models can use the RM-1 IR remote to control the shutter and a few other functions:
I reverse-engineered the RM-1 to implement the same functions on an Arduino Diecimila using only an IR LED connected between pin 11 and ground:
Here's a zip file containing the sketch (olympusrm1.pde and irparams.h):
Several macros are defined to emulate the buttons on the RM-1. most notably:
The remote uses the Extended NEC IR protocol.
Connecting a high-power IR LED as shown (without a current-limiting resistor) results on an "on" current of about 80ma. This exceeds the spec of 40ma for Atmega168 output pins, but the duty cycle is low (50% max during pulsing) so it's probably OK.
The range of the setup as shown (LED is Vishay TSAL6100) is about 25 feet, not quite as much as the RM-1 range itself. But it works well within that distance.
Using an Olympus E-510 DSLR as shown, I estimate that there's about a one second lag beween the IR command and when the shutter actually fires.