Mac OS X Leopard only: One of the built-in Mac utilities that got the most feature additions in Leopard—albeit pretty quietly—is Preview, the PDF and image viewer. We've already covered how you can do more with Preview in Leopard, but Mac OS X Hints points out another good one: image annotation. Add arrows and notes, or circle and outline areas of an image in Preview using the Annotation menu. (In Preview's View menu choose Customise Toolbar, then drag the Annotate menu onto the toolbar.) Then, when you're editing a non-PDF image in Preview, just select your annotation, and click and drag on the image itself. Handy, and no third-party software required.