ManOpen is a MacOS X GUI application for viewing Unix manual pages, which are the standard documentation for Unix command line programs, programmer libraries, and other system information.
ManOpen can be useful for opening a man page without dropping down to the command line, browsing and searching through long and complex man pages, or simply for printing them out.
Also included is an `openman' command line tool, which is similar to man except it will display the man pages in ManOpen.app instead of directly to the terminal.