This month @gr2m from minutes.io explains how the next generation of couchApps will bring distributed apps without thinking backend.
Imagine you could send emails right from your browser. You could save data to localStorage and it gets synchronized without you even thinking about it. Let users signup to your app, recover a password ... without ever touching a database. Sharing documents, converting files, upgrades to payed plans ... cloud's the limit! Sounds fun? Come by, grab a beer, and forget about backend.