Skim

Open source; $0

Current Version: 1.1.8 (July 1, 2008)

Skim is an pleasing, powerful and essential substitute for Adobe Reader that also happens to be free. It is a both a PDF reader and note-taker, designed to help you read and annotate PDFs. Features include:

• Viewing PDFs
• Adding and editing notes
• Highlighting important text, including one-swipe highlight modes
• Making "snapshots" for easy reference
• Navigation using table of contents or thumbnails, with visual history
• View all your notes and highlights
• Convenient reading in full screen
• Giving powerful presentations, with build-in transitions
• Handy preview of internal links
• Focus using a reading bar
• Magnification tool
• Smart cropping tools
• Extensive AppleScript support
• Bookmarks
• Saving passwords in Keychain
• Export notes as text
• Automatic download of remote PDFs
• Support for Apple Remote Control
• Interaction with LaTeX and PDFSync
• Integration with BibDesk
• Spotlight support
• Highly customizable

Version 1.1.8 adds/changes the following:

• You can now copy information about search results from the tables.
• Initializes line notes with default properties.
• Bring back children for anchored note text in note table.
• Ignore errors when reading notes due to unsupported extended attributes.
• Properly save line information in markup notes.
• Properly initalize rich text of existing anchored notes, fixes AppleScript support.
• Properly release the file when the document closes.