Google records your computer’s IP address, tracks all of the internet sites you visit and keeps this information until 2038 (much longer than other web browsers). Google has also pioneered a mechanism in its free Gmail service whereby they can scan your email, understand its content and provide contextual advertisements based on what you have written.
Honorable Mention: Scientists claim that the routine use of acetaminophen (e.g. Tylenol) is a leading cause of liver damage. Kind of makes your head ache, doesn’t it?