i am polishing an app that's "highly similar",
(a.k.a., nearly identical), so... first of all,
let me compliment you on your excellent insight. :+)
your website says "accounts coming soon". and i'm curious what that means. whatever it is, i should probably inform you that my app is javascript that works exclusively client-side, saving where you like, including your own site. (with a "last-resort" option to save on my site) and i will be encouraging people to _take_it_, for free (as in beer and speech), which means there might not be much money in this arena...
-bowerbird