If you scan documents to PDF or have to manipulate PDF files on any kind of regular basis, check out PDFPen and PDFPenPro for Mac. It can scan multiple documents straight into a PDF (where you can then edit them) and then email the PDF file you created directly from PDFPenPro. It also has a library feature where you can keep scanned images you wish to add to existing PDF documents (scanned copies of your initials and signature for contracts, watermarks, etc.)
Geoff Perlman is the CEO of REALSoftware a leader in Cross Platform Development Tools.