Reversed pictures in Photobooth!
One of the thing that I only realized lately is that PhotoBooth actually captures the picture reversed (like in a mirror). You don't really see it most of the time. You can really see the problem if you are taking a picture of something that has text on. There is a nice option in the Photobooth menu that will let you flip the photo instantly. If you don't want to worry about that all the time though, you can simply choose "Auto Flip New Photos" from the Edit menu. You'll see the same thing than usual until you take the shot. It will flip it only when it is captured.