So let me tell you about one of the many reasons I really like LOST!.
I was watching TV about 15 minutes ago and saw a commerical for Oceanic Airlines. If you are a follower of LOST! you may recall that Oceanic Airlines is the airline that crashed on the island in LOST!. The commerical had a website URL at the end: www.flyoceanicair.com. Now even if you have never seen LOST! click on it and watch the video to the end. It's good stuff.
This isn't the first time they have done this. Two summer's ago it was an entire online mystery spread out all over the Internet through secret pages and clues embedded in some sponsers like Jeep. Last summer was something a bit similiar but required more cooperation from fans to work out. In both cases (and this one too) it adds back story and answers some questions (such as what those numbers mean).
Apparently this one just started. The first episode is what I stumbled on 15 minutes ago. The next one comes out in 18 hours.