Sorry, rs link now fixed!
RS.js is a client side API that supports user hosted (aka unhosted) storage, giving users ownership of their data, choice over where it is stored etc. Users can choose a remotestorage hosting service, or run their own remotestorage server.
By extending the client (RS.js) to talk to SAFE Launcher, any app that supports remotestorage can also use SAFEnetwork to store the user's data.
Added bonus: RS.js implements http://offlinefirst.org operation, so the app works with or without an internet connection, and data automatically syncs across devices.