Some folk who were around to see Bungie's first Halo page might recall some of the cryptic, random messages that appeared there. While they recieved a great deal of attention back then, they have been largely forgotten since.
However, Cannibal Harry has exhumed those messages, and posted a long, Crack Pipe Alert analysis of them that is one of the best yet. Using what might be time-stamps in the messages, he has built an interesting and plausible timeline, including what could be the origin of Cortana... definitely worth checking out: