PDFpen for Mac continues to improve. Today Smile released version 10 with several new features:

Adds watermarks
Insert Headers & Footers
OCR multiple documents in batch (PDFpenPro only)
New Precision Edit tool selects, moves, resizes and deletes line art and text
Improves move & resize of images
Enhances page number styling
Adds larger Library item view
Prettier drawing colors
Adds context menu options
Various improvements and fixes

My favorite new feature is the watermark function. I am kind of particular about the typography in my watermarks (surprised, right?) and now I can import and create my Futura based all-caps watermarks to my heart's content.

The app also got attractive new icons. Learn more about PDFpen 10 from Smile.

Finally, there's a screencast from yours truly.