Low cost stickers that can be activated then placed on items in the refrigerator to indicate how much time has passed. Should be feasible to develop for a qualified team and would save People a lot of food. Maybe the design exists and just needs proper marketing.
Easy, cheap, hassle free batch scanning of photographs. How many people have boxes and boxes of family photos that they only see once every 5-10 years? Get those things digitized and organized now cheaply and easily.
You know those people who fly over peoples houses, take nice photos, then try to sell them to the owner? Why not offer people a digital copy of their houses/property? Lots of applications for that. From games to interior decorating to planning renovations.
Methane can be produced using electricity from solar power. Which could be run in cars without much modification. This could reduce fossil fuel usage without having wait for internal combustion engine vehicles to be retired. Maybe a unit installed at home could provide fuel for an individuals commute at near zero cost after it's paid off? If not maybe large facilities could make and ship the fuel to be sold at gas stations. Some people would be willing to pay a premium for liquid fuel produced by solar(At least I would). It could become even more desirable if proper carbon regulations ever kick in.
A wikipedia for DIY things. Instructibles sucks. It would be nice to have a well organized and very large corpus of information on how to do things from the very general to the very specific. From various methods to repair a hole in sheet rock to replacing brake pads on a 1997 Volvo to gardening with lots of various individual plans for different home projects like Halloween costumes, knitting, and woodworking. The hard part is getting a large community of people to contribute to the making of it.
I could go on all day. Anyone can. figuring out which idea in the sea of available ideas floating around, then executing it. That's the hard thing.
