I've been playing with these RGB LEDs for a while, and actually did a mod that is more than a novelty. Yes, a useful, practical RGB mod!
I have several of the Tek-Tite Mark Lites (basically an environmentally and economically friendly chemical light stick alternative). By default they are an incandescent single-AA light with pretty pittiful output.
I modded several with "super bright" LEDs of various colors (Blue, White, Green, Purple/Pink), then got some replacement lamps to cannibalize and did some wilder ones like UV and RGB. The UV one by itself is pretty useless, but it gets interesting when I put various flourescent materials up inside the glow cone.
The RGB one on the other hand is a really excellent marker light. Eye catching, without being irritating like strobe type flashing markers are.
Here's an animated GIF showing the 3 colors.
And a Quicktime movie of the RGB sequence (5MB)
It's a very cool marker light now, and quite mezmerizing to watch ('course, some flashaholics find a plain old white flashlight mezmerizing to watch). /ubbthreads/images/graemlins/icon6.gif
Aloha, iG