Originally Posted by PIT_Flyer
Also, I don't imagine my clients being too thrilled about me asking them to use Omnigraffle and dump their Visio documents.
OS X allows you to save any document as PDF really easily.
Just go to file->print (command-P) and select the PDF button from the bottom-left of the print pane. A number of options will drop-down, including save as pdf.
Very handy.
Also, keep this in mind for online purchases, as there's an option to save a document as pdf to a folder called "webreceipts".