Cosmeticdatabase.com is a pretty nifty website that basically rates thousands of cosmetic products based on their toxicity, cancer causing ingredients, allergy potential, etc. They also tell you which products were tested on animals and which weren't.
For all those OCD hypochondriacs - this might not be the site for you.
I played around with this site for awhile and discovered that I am slathering my face and body with so many hazardous ingredients I'm surprised my skin hasn't started melting off.
In all seriousness this is a really great site, especially if you have allergies. It rates each product 1 through 10 but then also provides a more detailed breakdown when you click on the product. It describes what each possible toxic/carcinogenic ingredient can do to your body.