Justin Williams lists three really good criteria (from a really good programmer) to make a product:

1. It’s something I want. (I’m selfish).
2. Either no one is doing it, or no one has hit a home-run. (I’m ambitious).
3. It could maybe, possibly theoretically be used by my mom. (I want to be loved).

#1 is a good reason. #2 and 3, as Justin points out, make it profitable (and possibly a business). Justin’s latest app is Photos+. Check it out in the App Store.

—

disclosure: I know Justin.