Dropbox has added two-factor authentication in a pre-release version of its software. The two-factor method requires a password plus a token delivered via another means, such as SMS or a special code-generation iOS app. At Macworld, Dan Moren explains how to use the new option, which reduces the chance of third-party break-ins, as a password alone no longer provides access. But note that AgileBits is recommending that 1Password users who rely on Dropbox for syncing passwords hold off for now. follow link
Option-click to Hide Apps Quickly
This trick has been available in the Mac OS for years, but many people still don't know it. If you have too many windows cluttering up your screen, you can hide specific ones easily as you work. When you're in any application, hold down the Option key and click on another app's window, on the Dock, or in the Finder to switch to that other app and simultaneously hide all the windows in the previously current app.
Dropbox Two-Factor Login Explained by Macworld