I was curious if anyone has been following the ARG for Nine Inch Nails new album, Year Zero. The album takes place 15 years in the future (2022), and it isn't too nice of a place and time to be living. Pretty much imagine if world and national events continue on their current course, and you've got an idea of what's going on. Anyway, there have been websites, found usb drives, phone numbers, emails, videos, spectrograph analysis of audio and video, Morse code laced into emails...all sorts of crazy things. As far as viral campaigns go, its pretty amazing.
The album finally leaked out this past week, and was posted up on NIN's website the next day for high quality listening. If you haven't heard it, check it out; it's very good.
edit: If you want more info, check out the Echoing The Sound forums, or the NIN Wiki.