The iPhone contains every piece of information you could possibly need, and in that sense it compares to the fictional encyclopedia The Hitchhiker’s Guide to the Galaxy. Douglas Adams, the author of the books in which it appears, wrote this about it:
“The Hitchhiker’s Guide to the Galaxy” is a wholly remarkable book. It’s already supplanted the Encyclopedia Galactica as the standard repository of all knowledge and wisdom, for two important reasons. First, it’s slightly cheaper; and secondly it has the words DON’T PANIC printed in large friendly letters on its cover.
Turn your iPhone into your own Hitchhiker’s Guide to the Galaxy using these wallpapers. The space below the logo can be used to insert contact information, in case you lose your phone.
[Edit October 13, 2011: High resolution versions of these are now available here.]