Vimeo member LoweRuno Productions adds a bit more reflective material into some inexpensive Halogen shop lights for a better spread. Aside from these lights running really hot and requiring a bit of voltage at your location, they can offer some really great results. The hardest part is diffusing the light output and color temperature to something more usable. Of course if this is your only source of light, you can do a simple white balance.
Take it all a bit further, here's another great DIY video left in the comments on adding Dimmer controls. This one comes from YouTube member aadailey. I've seen the simple inline DIY's but this in-housing is a nice mod that keeps the dimmer with the lights at all times. Don't forget that not all dimmer switches are created equal. Make sure you choose the right dimmer to handle the ratings on your shop light.