I'm always looking to create some new niche site for passive income. I've tried various site worth estimation services to see how much existing ideas are earn, but it's really hard to trust the numbers. Many of them are opaque about their methodology. But what if we aggregated their results (a la Nate Silver)? I created MetaSiteworth to do just that, and the results give you a ballpark idea about what kind of sites make what kind of money:

Here's some of examples:

// Music sites

http://metasiteworth.com/report/anydecentmusic.com

http://metasiteworth.com/report/rapgenius.com

http://metasiteworth.com/report/pitchfork.com

http://metasiteworth.com/report/mp3skull.com

// Utilities

http://metasiteworth.com/report/converticon.com

http://metasiteworth.com/report/favicon.cc

// Reference Sites

http://metasiteworth.com/report/howjsay.com

http://metasiteworth.com/report/urbandictionary.com

// Other

http://metasiteworth.com/report/milevalue.com

http://metasiteworth.com/report/mtbs3d.com

http://metasiteworth.com/report/thottbot.com

http://metasiteworth.com/report/forbiddenplanet.com

I think it's a brilliant idea. Popular estimator sites are making real passive income, in that there's not much work to be done after launching. The snag is this market is saturated and there is a low barrier to entry to keep competitors out. That said, I've never seen a site take an average of the most popular estimator sites. I think it's a clever angle, and it certainly creates the perception of a more accurate result. I'd use your site over your competitors.

Your challenge is going to be in gaining market share. Meaning, you need to rank high in Google! Or spread virally. That'll be tough, but I think you can do it with this angle.

Off (too low) by one order of magnitude in our case (as far as the income is concerned) ... Note that the title here says "income" while the website says "value of a website".