Do we really produce anything worth keeping for million years?
Plus, I'm in agreement with Les on visual aspect. Almost all recent technology involve encoding visual image to some kind of form that will require special device to read and an algorithm to decode so we can turn them back into visual images. How are we going to keep those hundreds of different encoding method and reading devices for millions of years? I think we really have a problem here. In few millenniums, future generation won't know much about us, unlike the way we know about our ancestors.