I've had a non-fixable problem twice.
First time was in 2000. A car driven by some 80 year old woman forced me into the curb, bending my derailleur hanger (aluminum). Tried to slowly straighten it by hand (wrong, wrong, wrong) and it snapped off. My wife was at work and wouldn't get off for about 4 more hours. Bummed a ride home (11 miles) with a good looking blond (about half my age
) who was driving a Mazda Miyata convertible. That was tough.
Second time was last summer (2009). Had 2 flats (1 front, 1 rear) within 1/2 mile. This required me to use my spare tube and patch a tube. About a mile past that point I had a blowout caused by a cut in the sidewall of the rear tire. I didn't see it when repairing the rear tire the first time. Had to call my wife. Luckily she was home and I was only about 3 miles away.