I mentioned the 20th birthday of Internetwork Protocol (IP) in this blog, so it seems fitting to mention the death of the 6bone. (At the risk of being known as a the Cliff Clavin of Internet history.)
The 6bone is (was) an experiemental network developed to allow people to deploy IP version 6 in a test environement. Initially they tunneled this protocol in IPv4 (the current IP address type... xxx.xxx.xxx.xxx) and later they deployed native IPv6 devices on network links.
May she rest in peace, and thanks to everyone who worked on this project.