i've not read any books on it, so i'm just going to throw up what i use and read for quality information and inspiration online:

http://www.zeldman.com/ (and his book)

http://www.alistapart.com/

http://www.cameronmoll.com/

http://www.smashingmagazine.com/ (inspiration and tools)

http://www.thinkvitamin.com/

http://psdtuts.com/ (for photoshoppy help)