Preview

Preview is a program that comes free on every Mac. It is used mostly with pdfs - and had lots of cool things in it.

Customizing the Toolbar:
Check out the various features of Preview in the toolbar. With a document open, go to VIEW - Customize Toolbars. You can drag any that you use often, right onto your toolbar.

Annotation:
You can annotate your pdf documents with the items under TOOLS - Annotate (or drag the annotate option to your toolbar). Choices are to draw ovals or rectangles around certain items [|Annotate Non-PDF images]