While I've heard of several over the years in the media, specifics skip...but, I will share a few of mine...most of them seem good timing...
Ice Storm two years ago. I had just bought my generator, finally, a few months prior. Ice covered everything, and we lost power for 4 days (a lot for SC, considering it was an ice storm. Temps plummeted. A lot of folks in my neighborhood had to get hotels/go on base. I powered up the genny, brought in some clamp lights, a few space heaters. Kept the house a cozy 67 deg. Switched between the fridge and deep freezer to conserve on gas. The kiddos were even able to play PS3 :0)
Coming out of the tax office 5-6 years ago, when I was just getting into prepping, I had just recently assembled a small SK to keep on my EDC pack. A guys truck couldn't start. We tried a few of the normal things to no sucess. He said something about the key fob could be dead, and the ignition won't recognize. I just so happened to have a spare coin cell that his FOB needed in my SK, that I used for my PT Just In Case. Put the new coin cell in there, his truck fired right up!
Most recently, I was buying some spare fluids to keep in my truck. I knew my S-Belt had a few cracks, but still had some time left, but I bought a spare, as it's quite literally, the weakest link as far as the engine goes. fast forward 7-8 months, my S-belt busted in the parking lot. Threw the new one on, and I was back in business.
These are just some of the most recent, but I've had other small ones at work, etc., when I had the right tool for the job.