http://www.ludix.com/moriarty/psalm46.html
This is not a book. It is an amusing, witty and poetic talk lectured by veteran game designer Brian Moriarty at Game Developers Conference back in 2002. He's perhaps best known for the seminal work of interactive fiction, Trinity, for Infocom, and Loom for Lucastarts.
Definitely a very good, erudite and puzzling read about easter eggs that I thought of sharing. His other essays are awesome too.