PDF Studio is an easy to use yet powerful PDF editor. It maintains full compatibility with the PDF format and supports most PDF functions. It allows you to view, print, and search PDF files, review and annotate documents with text, graphics, and sound, scan to PDF, fill in and save forms, secure documents with passwords and permissions, merge, split, and assemble documents, convert Word, image, and text files to PDF, and add bookmarks, watermarks, headers, and footers. It is integrated with Google Apps and Sharepoint. The Pro version allows content editing, permanent manual redaction, batch processing, precision measuring tools, digital signatures, and preflight PDFs with PDF/X profiles.
Whyteboard allows you to annotate PDF and PostScript documents and various image formats. You can draw with common tools such as a pen, rectangle, ellipse, text tool, etc. You can draw shapes, which can be moved, resized, recoloured, etc. Your drawing history is stored, allowing you to replay it. Tabbed painting is supported, with each sheet having its own unlimited undo and redo operations. There are live-updating thumbnails for each sheet. Sheets that are closed can also be undone, restoring their data. Note controls, similar to virtual, editable Post-It Notes. A draggable, live-updating resizable canvas that stretches to whatever size you want.