On a PC, the best way I ever figured out (and that doesn't necessarily mean it's the best way, period) was to hit the printscreen button, open some sort of photo program, paste the picture in there, then trim it down to the area I originally wanted. But on a Mac, you press Command+Shift+4, then you can essentially take a snapshot of whatever part of the screen you want. The best part is that the resulting image goes straight to your desktop.
As a result, I've accumulated a few screen captures that are polluting said desktop, so I figured I'd throw them on the old blog so I can delete them.
First, an old Facebook conversation I came across the other day:
And a message I sent to Annie, lover of birds:
Next, the prompts that popped up during a recent Google search (the edits are mine, of course):
Here's an old one - the top Yahoo headline the day after Petraeus took over: