Google Docs

 Google Docs  is a free and fairly user-friendly document creating, collaborative editing, and sharing silo from Google that sometimes fails inexplicably.

Sharing unavailable
Perhaps the most important feature of Google Docs, collaborative editing, if often blocked, because of a "Sharing unavailable" error preventing you from sharing the document with others to edit together.

When you click the blue [Share] link/button in the top right corner, sometimes you'll see a spinning cursor for a bit and then this alert:




 * undefined: I have seen this error at least once a day when attempting to share a Google Doc with others. In comparison I have never had nor seen any similar problem with Etherpad.