Inventions I'd like to see: Solar / radiant heat rechargeable thermostat. Annoying to have to replace mine with a watch battery once every six months.
Dual-filament bulbs that only fire one at a time. First one burns out, second one still provides light (perhaps at reduced output?), but indicates it is in need of replacement somehow. Not necessarily needed for standard bulbs, but the recessed lighting in my current place needs this badly. Bulbs are expensive and I don't keep them on hand if I'm not going to need them. But when I do need them, I'd like to have a bit of notice to get them before I lose light in a certain area of my home.
Flux (brightness / color adjustment for OSX) for all lighting in the home. Adjust amount of lighting based on time of day.