Quick Draw - Annotate your screen

Quick Draw let you put lines, arrows, rectangles, circles and text straight onto your screen. Over any window. While screencasting or presenting, draw an arrow to the thing you're talking about instead of waving the mouse pointer at it. Before you take a screenshot, hold shift and drop a solid rectangle over anything you'd rather not share, so there's nothing to edit out afterwards. Press T and type some text if a shape won't do.