Our own Matt Mets has a great project up where he makes homebrew camera flash triggers with xBee radios:
A year and a half ago, I started dabbling with using off-camera flash units, in order to exact better control over the lighting in my photographs. Of course, to do this, I had to invest in some equipment. I was able to pick up some used flashes for pretty cheap on Craigslist, however there were only two choices for wireless remote controls for them: Quality but expensive (Pocket Wizards), or cheap and questionable (Cactus triggers). Of course, I went for the cheap ones!
Well, I got what I payed for, and they stopped working after a few weeks. Rather than toss them, I had the bright idea of replacing their guts with some xBee transmitters. This actually worked pretty well, but I didnâ€™t get around to documenting them until now. The idea is really simple- just configure the xBees in direct pin mode, and hook them up to the flash sync ports on the camera and flash. Using these transceivers, I am able to reliably pull 1/120th of a second sync speed (probably fine for studio, but not daylight), with an excellent range (something like 1/8th mile outdoors). Though they work fine, the construction quality is definitely questionable, so Iâ€™m kicking around designing new enclosures and having them printed.