Some very cool suggestions. And here I read this thinking I could add something, but instead read about some cool looking things I never heard about. My gaming day has been made! And its a Monday!
Of the ones mentioned that I have played or DMed I'll second Traveller (non-d20), GURPS (3E works fine and is often on sale for 50% off), and Shadowrun is definitely a blast and the advice about Deckers is spot on.
Others not mentioned. Chivalry and Sorcery, Rolemaster, RIFTS, and Synnibar. Lots of people may complain about RIFTS and Synnibar in particular, but I have had a lot of fun playing them. Only Synnibar meets your one book criteria though. RIFTS and Chivalry and Sorcery technically do too, and is probably the best way to go with RIFTS, but C and S really expands greatly (nicely) with the additional books. I guess you can play Rolemaster with just one book, but like C&S the additional books add a lot of good things to the game.
HARN is fun too.
I almost forgot to second Paranoia too.