Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file.
Full Specifications
What's new in version 1.5.11
Auto size circle and box notes around selection.
Hit '?' to view hidden shortcuts.
Change laser pointer cursor in presentation by hitting 'c'.
Support reading Skim notes in plist format.
New hidden preference to save Skim notes in plist format.
Support for Skim notes in plist format in skimNotes and SkimPDF tools.