Jonathan writes in and shares his Yongnuo RF-603 unboxing with a quick demo. The RF-603 is an upgrade from the previous RF-602 model. A single RF-603 can act both as a transmitter and receiver, as to where the 602 were actual separate units. This is definitely more convenient and also changes the required batteries to only AAAs (easily found at any store).
These are also Wireless Camera Shutter Remotes to fire your camera while on a tripod (best for sharper images). As you can see from the end of the video, Jonathan sets up the RF-603 to trigger both his camera's shutter while simultaneously firing off the strobe. Not only can they fire off strobes through a sync cable, but they also have a built in hot shoe for firing off Speedlite Flashes, which allows you to mix all different types of strobes in one setting. [Thanks Jonathan] You can find these inexpensive flash triggers following the link (click here).
Yongnuo RF-603 Wireless Flash Triggers