I just wish UNIX man pages were as well written and as all-encompassing as the online documentation available on my Lisp machine. Basically three or four feet worth of the printed manual set available at a keypress (or mouse click) or two, thoroughly indexed and cross-referenced, viewable directly at the command prompt (even while in the middle of typing a command -- invaluable when you've forgotten how something works halfway through) from within the editor, or inside the Document Examiner, with hypertext, formatting, diagrams, etc... a lovely system and well ahead of its time.