Yahoo says that it uses anonymization and doesn't give names or Web-browsing information to advertisers.

WSJ: They Know What You're Shopping For

But Marc Rotenberg, director of the Electronic Privacy Information Center, argues that a better standard for the details of anonymization is needed.

FORBES: Magazine Article

He could route all Bitcoin traffic through an anonymization service like Tor.

FORBES: How Private Are Bitcoin Transactions?

Anonymization services add another obstacle on the increasingly complex paths of botnets.

FORBES: Is Your Computer Enslaved to a Spammer?