it isn't a baby book as much as one for after the baby is here but I recommend the baby whisperer by Tracy Hogg it has great information about sleep training. I read it with my first and am re-reading in preparation for Baby #2 that is due in 5 wks.
I've been reading what to expect when you're expecting and baby bargains! Baby bargains is great because it goes through all of the best and safest brands for baby and tells you what items are just a waste of money.
Get Girlfriend's Guide to Pregnancy! Awesome read and good, down to earth advice!
Kaz Cooke- up the duff. It takes the p*ss out of pregnancy, pretty funny but also has serious.bits of info all throughout. Its a good read.
It's cliché but I read what to expect when you're expecting with my first. I found it helpful. Also Belly Laughs by Jenny McCarthy was not so much for information but just nice to find some humor in all of the things that come along with pregnancy.