My standard set-up is a Nikon D300 with a 50mm f/1.4 mounted on a tripod. On another tripod a SB-900 Speedlight (the updated model is named SB-910) is mounted with the standard SB-900 diffuser on and an additional white umbrella. You can also use a SB-700 Speedlight.
I can wireless tricker the SB-900 unit with Nikon's CLS (Creative Lighting System) and using the built in flash og the D300 as commander. But I have chosen to add a Pocket Wizard FlexTT5 to the SB-900 (Receiver) and a Pocket Wizard MiniTT1 (Transmitter) to the D300. On top of the PW MiniTT1 a PW AC3 is mounted (Light Power). In addition I have added a Nikon SD-9 battery pack enabling the SB-900 unit to recharge faster and extending the time the SB-900 unit can operate before battery depletion.
This is a more expensive set-up, but it adds a lot of versatility to the way I can arrange the flash unit(s) relative to the subject.
The external SB-900 flash set-up (sorry for the bad iPhone quality)
Here is two shots made with this standard set-up. In both cases the umbrella is to my right side and very close to my face (the closer the light source the softer the light!). The back drop is a white wall. I would have to direct a second light source to the wall to get it more white.
I know I'm not the best looking model, but which one do you prefere? My favorite is photo 2.