Sick of anonymous users screwing up your hard work on the Wikipedia? Virgil Griffith, a postgrad student at California Institute of Technology, created a tool that identifies anonymous Wikipedia editors based on the digital footprint left by their IP addresses.
Griffith thus downloaded the entire encyclopedia, isolating the XML-based records of anonymous changes and IP addresses. He then correlated those IP addresses with public net-address lookup services such as ARIN, as well as private domain-name data provided by IP2Location.com. The result: A database of 34.4 million edits, performed by 2.6 million organizations or individuals ranging from the CIA to Microsoft, now linked to the edits they or someone at their organisation's net address has made.
It's not an exact science, but Wikipedia Scanner can be used to unmask the identities of anonymous editors. If you want to edit Wikipedia, learn the ropes before you start.