I lost one of "my" shelter girls this week.
She came in as a stray around 3 years old, in rough shape (very hungry and dirty), and she was one of those strays who gets into the shelter and says "Hey...all I can eat, warm bed, lots of attention...this ROCKS!" She loved everyone and made friends instantly with both humans and other cats, very talkative and chatty...sweet, sweet kitty. She waited patiently these last couple of weeks to be spayed until she'd gained enough weight for anaesthesia, playing with her cage-mates and helping the volunteers with cleaning duties.
When she went in to be spayed, they discovered an enormous uterine tumor, and she was euthanized before waking up.
Please, spay and neuter your pets, for their own good health. There's no good reason this little girl should have died just because no one cared enough to spay her.
It's not an exciting or horrifying story, but it happens far too often.
Edited because I can't spell tonight.