I tend to use studio flash in the studio, but sometimes a location shoot doesn't need 1000ws or bags of heavy kit. I love my PocketWizard TT1 and TT5 units because I can simply get wireless TTL flash going with my Canon DSLRs. This simplifies the use of speedlite driven modifiers because I don't have to worry about flash splitters and the inconsistent function of IR based remote flash. This past fall, Westcott released a series of modifiers designed to be lightweight, portable and to work with hot shoe based flashguns.
The Canon 580 EX II is a fine unit, although my preference are Metz 58 AF-2 units. In either case they do the full eTTL thing readily. Stringing cables is a pain and IR triggers don't always work when the flash is inside a box.
Setting up either the Orb or the Striplight is a piece of cake. The kit includes a solid stand, a flash mount with tilt and umbrella mount, and the appropriate soft box and front scrim. Simply erect the stand, and attach the flash mount. Open the soft box, just like an umbrella and mount it to the stand. Place your flash on the mount using whatever trigger you like, orienting the flash to fire into the box. Put the scrim on using the velcro tabs. That's it!.
The boxes are constructed with zipped sections to allow the stand to pass through the side of the box. The orb is an octabox style and the strip light is a tall narrow style. The Orb has one opening, the strip has two, for portrait and landscape orientations.
Using the Pocket Wizards, you maintain full eTTL flash capability and by adding the AC3 zone controller you can set multiple zones through the pocket wizards avoiding the need to use Canon's zone system that is dependent upon infrared.
Great exposures are a snap and with proper light placement you can get beautifully soft light where the flash is the dominant source or even outside as supporting light. The really nice thing about the Westcott kits is how compact they are. You could carry four of them in a generic gym bag from Walmart.
Of course you can use cabled connections for your TTL flashes if you so desire, although I avoid this due to the probability I will knock something expensive over when I trip on the cable.
Both Westcott kits retail for under $200 and you can sometimes find them on sale. For the money, they are really well built, provide wonderful soft light and help you get more from your hot shoe flash.
Pictured are the Apollo Orb and the Apollo Strip Speedlite kits