Last year my '91 Regal’s radiator croaked. The repairman called me and told me flatly, “This car is not worth the price of the repairs.” I let him keep it and went and bought another one.
I had an '86 Taurus wagon the wife and I bought new. It was a great car until it hit 100K miles - and then it was like a timer had gone off somewhere because just about every system in the damn thing started having problems:
The gas gauge quit working.
The heater core went, taking a freeze plug and the water pump with it (and cracking the head just for good measure).
The AC stopped working
Two of the electric windows quit (thankfully, they were up at the time.)
The transmission started slipping.
It started developing rust in the damndest places - like around the door handles, halfway up the windshield, around the rear windows…
The trunk seal leaked so the well under the back deck was always full of water.
By the time the brakes’ master cylinder started to go, I had had enough. I drove it (just barely) to the junkyard. The tranny was slipping so hard that the engine was revving at about 8 grand even though I couldn’t get the car going faster than about 30 mph. At the junkyard, I had to stop by nosing the car into a Jersey barrier. That part was fun…did I mention that the seatbelts were gone, having been chewed off by a dog I once owned?
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=142053
1996 ford taurus, killed by a drunk driver
Another death by deer. Mazdas tend to crumple completely when they encounter giant Pennsylvania deer.
My most recent loss was due to scum sucking car thieves. The cop told me they probably had the whole thing broken down into unidentifiable pieces within an hour. The last I saw of it was a tiny pile of broken glass in the parking spot I had left it in.
A few cars ago, but it was a 1973 Cadillac Eldorado. Bought it for $550. Ran it up over 350K miles. It blew the rings in three cylinders. It still ran. Dealer gave me $1000 in trade for it. 
It was totalled by a gal who rear-ended me in her big honkin’ SUV.
And yes, I was in the vehicle at the time.
Same thing happened to me last year, except it was by a hit and run giant SUV. But I am alive, and that’s all that really matters. 
Horribly. Without dignity. Lingering 3-month death.
T’was a chilly January evening on my way home from work when my ‘benign’ engine tick of the last 90,000 miles changed into a ‘malignant’ engine click accompanied by an ominous light on my dashboard of an old-tyme oil can (check engine). I also noticed about a 20-30% drop in power from my 90 Nissan 4-banger. Before I could exit the freeway the click was accompanied by an alarming squeal. Once I was pulled over & looking around (and in complete denial of the obvious problem) under the hood I confirmed that all belts were OK and that a sleety, chilly night was no garage for a diagnosis. I hopped back in and started the truck and the noises were gone. I drove home.
For the next 2 months I wondered at the loss of power and the mysterious click which came back the next morning and took up permanent residence under my hood. Then one night on the way home the click turned into a screech. Not a slipping belt screech, but uncannily like the screech made when the locksmith is cutting a new key on his fancy key grinder. It was disquieting to hear this from my engine compartment. I stopped, restared the engine and no noise! Odd. When it did it again a week later I instinctively knew I had to limp it home for the last 2 miles before shutting it down. It passed away in the garage during the night. I sold it fo $400. Best $7,000 car I ever had. 
The car: 1996 Chevrolet Blazer LT
The time: February 2003
I had left CSCC and was almost to work (a school district). When I was two miles from work I begin smelling smoke. I pull over and get out to discover smoke pouring from my engine bay. My car was on fire. I called 911 and they dispatched a fire crew and a deputy sheriff. The deputy arrived in under 3 minutes and although I was less than 2 miles from a fire station it took them about 10 minutes. I sat in the sherriffs cruiser and watched my poor car burn itself to death.
I really feel sorry for that car, poor thing had 2 years till retirement.
I ended up replacing it with a 2000 Bravada. I’d rather have my blazer back.
My first, and last, car was a’97 Camry, maroon, V6. Not very sexy, but extremely reliable. Driving in the left lane on the DC beltway one night, in the rain, heading into a turn. All of a sudden my brakes don’t work, and the next thing I know, the front end and the back end of the car are no longer moving the same way. We did 2 complete 360’s, hit the jersey barrier at least 3 times, and never slowed down at all. I managed to get the car under control, and pointed the right way (still without brakes) and pulled over to the side. The damage estimate was about 120% of the value of the car, and we didn’t even set off the airbags. Fortunately, we didn’t hit anyone else, either, which is pretty amazing if you know what beltway traffic is like, even at 10PM on a friday.
1987 Chrysler…drove it forever. Nickeled and dimed me, and then started to $100 and $500 me, and then, one day after driving down a busy highway, up a busy street, in the rain, in rush hour, that car literally died inches from my parking space in my apartment building. The poor thing made sure I got home and then it just crapped out.
Transmission.
There was nothing we could do.
The gas in the tank was worth more than the whole car.
My beloved 1987 Mitsubishi Tredia, Max, died on Christmas Day, 2001. It was almost midnight, and I was driving back home from my parents’ house (240 miles away) because I had to work the next day. Max started sputtering right after I exited the Florida Turnpike. He managed to live just long enough for me to pull into a store parking lot.
The worst part: I had spent almost $800 on repairs the week before. His Blue Book value was about half of that.
The tires were shot out by state troopers.
My 93 Saturn died protecting my wife. She had borrowed it, and was the third car through an intersection when some clowns ran a red light and hit her right in the driver side door. It buckled as it should, so she was only in the emergency room for a couple of hours, nothing serious. The insurance adjuster said it was the worst crash he had ever seen without someone being seriously hurt.
Before that, I had a '91 Datsun station wagon which was basically rusted out. One guy in my department, who stood no more then 5’4" and weighed about 90 pounds pulled the rear passenger side door off its hinges. The accelerator finally stuck one day, and while I got it to stop without hitting anything, I decided it had it. I brought it for a trade in. The dealer looked funny at me and offered $100, which I was glad to get.
Mr S. was coming home at night in his trusty little S-10 pickup, when a deer decided to commit suicide by grill. The truck kept running, but the gas and brake lines were so corroded that the impact disintegrated them. Too expensive (labor time vs. worth of vehicle) to fix.
Before that, I was driving my cute little fuchsia Aspire, my first new car, the first car I bought with my own money, my one-year-old baby car, to my part-time job, the one I’d taken after quitting my hated full-time job to start my freelance career. It was a beautiful sunny day, one week after I’d quit. I’m toodling along just under 60 mph when Bozo in his Jeep pulls out from a dead stop at an intersection with perfect visibility, right in front of me. I had very little time to brake. Air bags are a wonderful thing. The car was totaled and I had a little scratch on my hand. I bought another Aspire. It’s got 160K miles on it, and I’ll miss it when it croaks.
Hit by a dump truck runing a stop light.