Here is a cool tip for all of you creative writers. If you are using a cocoa app (TextEdit, Pages, etc.), press Command-T. That will bring up the incredibly useful type panel. Here you can change font sizes, typefaces, colors, etc.
But what if you have a document with multiple font sizes, and you want to scale them all proportionately? If you were to select your text and specify a size, all of your text will change to that size. Here is the tip: select your text and use mathematical functions in the size box to scale the text. For example, if you want to multiply all your font sizes by two, type *2 and the font sizes will resize accordingly without changing all the font sizes to the same size.
You can also use other functions, / divide, + add, – subtract, * multiply. Have fun scaling those fonts!