The just revealed discovery of several other never given contingency speeches written by William Safire. Such as "In Event Astronauts Abscond With Spacecraft."
http://xkcd.com/1484/
Another XKCD classic. I think my favorite is Columbia landing directly on the USS Hornet and crushing Nixon, and President Agnew giving the speech. Which sets up the alternate history of no Watergate BUT a real possibility of a impeachment due to Agnew's corruption...
Okay, I'm thinking this one through too much.