If you are considering investing in a wireless flash system, here is a list of gear to help get you started. This is a versatile one light setup that's effective for a large array of assignments. I've used this with an umbrella for portraits, and without it for interiors, and nature photography. While this list is for Canon systems, I expect the Nikon compatible Pocket Wizards to be available soon.
1) Pocket Wizard Transceiver for Canon
B&H # WIFTT5C
With this particular pairing (#1 and 2), you can take advantage of Canon's ETTL system wirelessly. This can be a major convenience over Manual flash. Just set the Transceiver to the same channel as the Transmitter (see #2), and your flash will fire every time you press the camera's shutter. This piece has a ¼ inch thread so it can be mounted on any standard light stand. The flash is then attached to the hotshoe on top.
2) Pocket Wizard Transmitter for Canon
B&H # WIMTT1C
This piece slides into the hotshoe on your camera. It's controlled by a radio frequency so it can fire the flash from just about anywhere.
3) IMPACT Light Stands
B&H # IMLS6BQ
These aren't the fanciest stands, but they do the job well. If you're using them outdoors add some weight to the bottom so it doesn't blow over.
4) Medialight Universal Umbrella Bracket
B&H # MEPGSH
This gadget holds your photo umbrella so you can create a soft, diffused quality of light for portrait subjects.
5) Stroboframe Flash Mount Adapter
B&H # STFMS
This small piece will be mounted on top of the Umbrella Bracket (see #4)
6) White Shoot Through Umbrella 33”
B&H # IMU33T
By shooting through a white umbrella, it's easy to create nice big catchlights in your subject's eyes.
7) Canon 580 EXII Flash
B&H # CA580EX2
By far, the best flash I've ever used. It has incredibly fast recycle times, and provides enough light to handle most photographic situations.
TOTAL = $932.84