Here is a great little Mac OS X app for editing PDFs: PDFPen from Smile On My Mac.
Some of its features:
- Replace text in original PDF with editable text blocks
- Fill out and save PDF forms
- Move, resize, copy and delete images in original PDF
- Copy and paste rich text; retain fonts and formatting when copying
from PDFs - Select and copy text across multiple columns
- Overlay text and images onto PDF (for example, sign purchase orders
by applying signature image) - Show PDFs in single, facing-page, multi-page, and multiple facing-page views
- Insert and remove pages; re-order pages in a PDF by drag & drop