I also use the Britek lights/softboxes, in conjunction with worklights. A couple of things to add are dimmers and flags. With dimmers, you can quickly put strong and fill light where needed, without moving everything. Not only that, you can see your changes in real time.
You can add shadows to a scene with flags and gobos. Flags are just pieces of plastic, wood or metal that you can put in front of a light to block off certain portions. For instance, you can flag the top and lower halves of a light, to create an "eyelight". I've actually done this with a scoop/clamp light.
Remember that a lot of sound stages have light riggings on the ceiling. These create "hair light", which will create a nice outline of your actor's head. It's easy to think in terms of natural, motivated light, like a lamp on a dresser, but hairlight only happens from above or behind. I think it is one of the most important angles to light. Steve Kaeser sells some nice, tall, telescoping boom stands to mount such lights on.
"Backlight" is like "hair light", but from a lower angle. Sometimes the lights are shined up from the floor and they can outline a subject's body. Just think of all the shadow work you can do with just those two kinds of lighting.
Adding just a little bit of fog will catch light rays, especially if you are using flashlights, car headlights, etc. It is only recently that I've been thinking about creative lighting. I was notorious for just shining bright lights, which were often mounted right on the tripod, along with my Super 8 camera!
I asked the producers of WITCHES' NIGHT how they lit their outdoor night shots. They put a 2000 watt light on a cherry picker (rental crane/genie) and used blue gel sheet for an overall moonlight effect, then they placed fill lights in key spots. It worked very well and is a cheaper option to the 20,000 - 50,000 watt lighting cranes that Hollywood shoots use for moonlight.