Create Your Own Horrific Green Lantern, Upload Your Oath and Play an Astronomy ARG.

Here are some of the promotional activities the Green Lantern Movie has to offer.

Personally, I dig the Green Lantern Creator. Where you can make all manner of nightmarish
Alien Lanterns. Here's mine -- Luuv Kraftia of Sector 902.

You can also upload a video of yourself reciting the Lantern Oath @ The Infinite Oath.

 Or get involved with an Astronomy ARG that starts here @ http://www.newtonastronomers.com/.

And includes a link to Dr. Amanda Waller's personal blog.