Fogpad
Since July 2013 we've been working on that mission, and the result is what you see today: a fully featured web app that takes advantage of client-side encryption in Javascript. Fogpad integrates with Google Drive, so anyone can seamlessly move their documents to the service to keep them secure and private. We use industry-standard encryption systems to make sure that your data is secure always, but our ultimate goal is to make the security layer as out-of-the-way as possible.