I use the Lowel Light Array (
http://www.lowel.com/lightarray/) which I purchased at B&H Photo in NY. It's attached to the wall using a Bogen wall mounted boom arm (
http://www.bogenimaging.us/product/t...=229&itemid=50) also purchased at B&H. You can see the pictures below.
I use this primarily to illuminate my canvas since the overall effect is very soft. I usually rig sheets to block the light from hitting the model and put a separate light on the model. I use 18 inch Lumichrome bulbs in a smaller fixture. A smaller fixture gives sharper shadow edges.
The Light Array illuminates my photo reference as well as my painting.
The color changes very little from day to night since the color temperature of the Lumichrome bulbs is closly matched to north daylight. As I mentioned earlier during the warmer months trees outside of my north window block the skylight so I really depend on these lights.