I took another fabulous workshop from Douglas Sonders, a local professional photographer that has created some very interesting commercial work - from cars to celebrities and from ads to covers.  After taking his class on off camera lighting, I now realize how much impact just one and up to as little as three lights can have on your shot. Prior to this understanding, I had looked at some of Doug's work and erroneously assumed he had manipulated the shot in post-production with Photoshop. While that may be the case on some of his work, I witnessed how he built a photo composition one light at a time to generate an amazing photograph using a student from the class and things in the environment, both inside the classroom studio and outside in the parking lot. The preview of the photo on his camera was near perfect with little or no post touchup action required.
Before setting up, Doug, first, walked us through the various equipment. In many cases, there really isn't a need to spend a lot on lights, and you may be able to find much of what he used on ebay or craigslist. A basic setup includes the lighting stand, the light itself, transmitters to sync the flashes, and a couple light modifiers. For transmitters, Pocket Wizards, Radio Poppers, and Cactus transmitters seem to be popular. You will need at least a pair, one for the first external flash and one on your camera hot shoe. Additional devices are needed for more lights, obviously. Next, the setup requires the actual lights, themselves. The brand Doug uses are made by White Lighting, but Alien Bee makes more affordable models that produce similar results. Finally, the basic setup is completed with light modifiers, like beauty dishes with honeycomb grids, reflectors, soft boxes, and umbrellas. It's not necessary to buy all of this equipment, though. In fact, websites like borrowlenses.com will rent them to you for various durations. 
My favorite composition of the day was shot outside with a student leaning against a car.  Doug used one 3200 watt light with a beauty dish and wide honeycomb grid on the subject's face, one 3200 watt light with a reflector from behind and to the right of the subject, and one additional light with a reflector aimed on the rear car light that was on the opposite side of the car from the subject. Unfortunately, I don't have a copy of that photo, but we did set up an environmental shot in a supply room in a similar way, adding a fog machine to accentuate the directional aspect of the lights and lights in the background on modeling mode (a softer light used for posing) to tell the story of the photo.  By the time I got to shoot the subject with my camera and the lighting setup, the fog machine had created too much of a haze to get a clear photo.  My shot isn't terrible, though.  I could have been a bit lower to the ground.
What you can see, though, is the impact of the light that frames out his face, and the rear reflector light that highlights his shoulders and hair to make him, the subject, stand out from a noisy background.  Neat, right?  Now I just need to recruit some people, rent some equipment, and practice!