Andy Baio explains how he tracked down a trolling "anonymous" blogger who revealed his identity by using a Google Analytics ID that was incremented one up from his public blog. He uses this as a springboard for offering practical advice to people who want to blog "anonymously" (or, at least, as anonymously as possible):
1. Don't use Google Analytics or any other third-party embed system. If you have to, create a new account with an anonymous email. At the very least, create a separate Analytics account to track the new domain. (From the "My Analytics Accounts" dropdown, select "Create New Account.")
2. Turn on domain privacy with your registrar. Better, use a hosted service to avoid domain payments entirely.
3. If you're hosting your own blog, don't share IP addresses with any of your existing websites. Ideally, use a completely different host; it's easy to discover sites on neighboring IPs.
4. Watch your history. Sites like Whois Source track your history of domain and nameserver changes permanently, and Archive.org may archive old versions of your site. Being the first person to follow your anonymous Twitter account or promote the link could also be a giveaway.
5. Is your anonymity a life-or-death situation? Be aware that any service you use, including your own ISP, could be forced to reveal your IP address and account details under a court order. Use shared computers and an anonymous proxy or Tor when blogging to mask your IP address.