The mass evacuation, and the resultant massive traffic jams, in large portions of Texas preceeding the landfall of Hurricane Rita. Many people ran out of fuel and were forced to camp out on the side of major highways and fend for themselves.
Hurricane Rita (the "other" Hurricane) made a last-minute Easterly turn. Bad news for East Texas and West Louisiana. Good news for those camped out on highways further West in Texas.
My friends and I pretty much avoided the Texodus by taking tiny back roads.