Here's Paula Begoin's web site:
http://www.cosmeticscop.com/default.asp
The book is really better than her website, because she independently examines and tests each product (makeup, skin care, and hair care). She lists ingredients that are good and bad, what works, and what is worth the money.
The book is big and expensive, so I always just sneak into my local Barnes & Noble if I want to look something up. E.g., I need new blush, but want to know what's recommended.
My beauty tip for the day:
Lots of water and enough sleep do wonders.