westfw:
From reports that I've seen, more people are abusing their AVRs and having them appear to survive (ie by driving LEDs directly with no current limiting resistors), than are having their AVRs die from momentary overloads.
Yep. AVR chips seem quite resilient to having their output pins shorted to ground. It's a good thing too, when you see the abuse they get (keep reading these forums for horror stories...)
Aside: I wonder if the designers knew this?
They even seem to survive being plugged into the socket backwards. Atmel didn't put the VCC/GND pins diagonally opposite each other - a common trick used to kill chips in the old days (eg. 74LS logic chips).
OTOH don't assume this is 'normal' for electronics. Many chips will die instantly at the slightest abuse.