With more and more paperwork happening without the paper, your control over those PDF files becomes more important. What’s frustrating is that you can’t edit, write on or draw on PDF files like you can with paper, even using some professional PDF programs. PDFpen from SmileOnMyMac allows you to do almost anything with a PDF file, and then save it back out as a PDF file. So you can mark up or simply sign a PDF document. Very handy.