Here's a new one for me. Audi are introducing their new A3 car. But to develop interest, they have an ongoing story about how a specific car was stolen from them. To quote from the site, it is “a fun, interactive, fictional story sponsored by Audi. This campaign is similar to what's known as "Alternate Reality Gaming," in which a community of users become a part of the story, interact with its characters, and help each other unravel its mysteries along the way. If you'd like to immerse yourself in this entertaining, challenging experience, you can check out the "In A Nutshell" links on the right for a summary of the story so far...then be sure to visit the discussion forum and join in the fun!”
The story is presented in the form of a blog, with some movies, a discussion forum, RSS feed, links, etc. -- cool!