Sometimes the most useful hacks are also the simplest ones. A case in point is the LED and resistor assembly that [Skippy] recently posted on his blog. The idea is to solder up some pre-made ...

Without a resistor, LEDs tend to shine too brightly ... So you already have your circuit set up and the Arduino sketch ...

[Computergeek] made an Arduino Shield in order to use ... he should probably have invited a resistor to the party the two IR LEDs are having.