If you don't have installed program for editing PDF documents on your computer, then you can use web application PDFescape which allows you to edit your documents in your browser.
Did you know you can use your camera with Adobe Lightroom to shoot photos and display them directly on your computer screen? It's called shooting in tethered mode.
Is it really hard for you to ignore that beep sound of a new email, Facebook notification or a text message, are you experiencing an urge to share the latest photo to Instagram or send a new tweet?
If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.
Neat little trick to force the preview images of running programs in Windows 7 taskbar or a so called Aero Peek, to show instantly with no delay at all.