Aliens, ancient civilizations, lasers, and...Yahoo?

It's not every day that a major dotcom decides to try to communicate with aliens from atop an ancient pyramid. With lasers. But that's exactly what Yahoo will be doing on Oct. 25, and it wants you to help piece the message together.

Starting today, visitors to Yahoo's Time Capsule site can choose what photos, video, sounds, or images they want to see preserved for posterity. The time capsule itself will be sent to Smithsonian Folkways Recordings in Washington, D.C. But selected contributions will be beamed onto the Teotihuacan pyramid in Mexico and simultaneously beamed into space via laser. Yahoo's hoping that maybe an extraterrestrial being or two are listening.

The event will also be webcast, for those of us who are neither in Mexico nor outer space.