Peter Merholz bought an original Macintosh User Manual on eBay and scanned it for your viewing enjoyment. Check it out here: Link - via Core77
In a similar vein, the chapter introduction pages in the NeXT owners' guide are also good fun: http://www.flickr.com/photos/brrm/sets/72157601854846146/
http://www.flickr.com/photos/brrm/sets/72157601854846146/