As you probably know, Mac OS X comes with a built-in *.pdf viewer, Preview. However, as great as that program is, it has one flaw — it won’t combine multiple *.pdf files into one. Fear not though, a free program called Combine PDFs does this just fine. It allows you to drag and drop *.pdf files into its interface, where you can then rearrange and rotate files as necessary or desired. I have used this program, and it performs its tasks quickly and easily — just like Mac software should!