Expand and contract notifications (Jelly Bean)

Android 4.1/4.2 "Jelly Bean" gives you a good amount of control over your notifications -- and in a lot of cases, you can deal with them without ever having to switch over to the appropriate app. If you've missed a call, you can return the call or respond with a text message, right from the notification “shade.” If you've got a new email, you can read the first few lines of it without launching the mail app (just slide two fingers outward to expand). You can even access your settings straight from the shade -- just tap those sliders up on the top of the window.