I run the Bedbug Registry (http://bedbugregistry.com), which covers about half my living expenses. Every six months or so I put in a week's work on it; otherwise it's just a matter of site babysitting (irate landlords, requests to rescind a report), which takes no more than an hour a week.

Getting the site to this point took about two years, so I would counsel patience and perserverance. It also helps to really care about the project, even if you don't spend much time on it.

And it especially helps when your business partners are relentless insects who spread very efficiently and feast on the blood of people's sleeping children.