You can use just about anything that is designed for use with "hot" lights (tungsten), such as heat-resistant umbrellas and heat-resistant ventilated soft boxes, as well as with "cinema" gels. Heat is the main problem with work lights, as well as with more photographically-oriented tungsten lights (blondes, redheads, Omni, Tota, Arri 650 fresnels, and so on). They're pretty good at setting fires at a distance if you're not careful about what they're hitting; things like fabric and paper that don't have a lot of mass compared to their surface area (and are flammable) make especially good kindling and won't give you a lot of warning (charring, smoke) before they go up in flames.

As long as you're careful with them, they'll make good lights. You just don't get all of the DIY goodness that, say, good fluorescents will give you since you lose a lot of things that would have made good diffusers and reflectors because of the heat issue. Distance cures a lot of the problems, but it also loses you a lot of light -- and it requires, well, distance, which is often in short supply in a home-studio environment. Oh, and no matter how careful you're being, always have a fire extinguisher handy (not on the other side of the room); a little bit of unnoticed dust can cause a very big emergency in a very small amount of time, and it's a lot easier to clean up extinguisher residue and maybe sand out and refinish a dime-sized scorch mark than to replace your house or garage.