This is a tiny project from about 1 year ago. I wanted to add extra IR-light for my DV camera's night shot mode. Very useful when playing in dark and smoky clubs.
I bought 10 Osram high power IR LEDs (SFH4550) and found 5 small resistors (47 Ohm). I run it off two 1.5V batteries.
Below a picture and the schematics.