If you use Dropbox or Google Docs you are committing privacy suicide. You might as well be storing all your files and selfies on the home page of a public website or emailing them directly to email@example.com. If you are finished contributing to mass surveillance, there are a number of providers that offer encrypted zero knowledge cloud based storage listed below.
"Dropbox is hostile to privacy, unlike 'zero knowledge' SpiderOak." - Edward Snowden
SpiderOak is a zero knowledge encrypted cloud storage. That means that SpiderOak does not have any knowledge of what you store or backup in the cloud, but nor do they keep your key and password. So watch out, if lose your password SpiderOak cant let you back in, they simply dont have the key. Up to 2 GB is free and you can share files, sync and do backups of computer and phone.
Wuala is a zero knowledge cloud storage based in Switzerland outside the US and EU jurisdiction. They use AES- 256 for encryption, RSA 2048 for signatures and for key exchange when sharing folders, and SHA-256 for integrity checks. You are allowed up to 5 GB free and can sync, share, and backup as well.