I'm a big fan of Google's two-step verification process, and it seems that cloud-based storage giant, Dropbox, have followed through with some added security of your precious data by enabling two-step verification.
In order to turn on the feature, you'll require the most up-to-date beta desktop version of Dropbox's client. Once you've acquired that, you can jump over to the Dropbox website, and enter the beta, where you can turn on the two-step verification.
It works pretty much identical to Google's two-step verification, where you'll be prompted to enter a limited-time, one-use password that you can receive by text, or an app similar to Google Authenticator. If you were to lose your phone, you would get a one-time use backup code, but there's only one, so you'd have to be very careful where you put it.