"chip plugged in backwards... check!"
I don't believe that actually kills it - here's what gets connected when flipped:
F - flipped port, N - normal port
F N
b1 c6
b2 d0
b3 d1
b4 d2
b5 d3
avcc d4
aref vcc << aref possibly damaged with 5V applied and no Vcc
Gnd Gnd << Good!
c0 b6
c1 b7
c2 d5
c3 d6
c4 d7
c5 b0
c6 b1
d0 b2
d1 b3
d2 b4
d3 b5
d4 avcc << d4 possibly damaged with 5V applied and no Vcc
Gnd Gnd << Good!
b6 c0
b7 c1
d5 c2
d6 c3
d7 c4
b0 c5
So 2 pins may possibly be damaged from having 5V being applied while Vcc was not.
If other pins had 5V from external sources applied, those might similarly be damaged.
I've plugged in chips backwards a couple of times, then put a big "1" on my duemilanove (back before I went custom everything)
and neither time did the chip get warm, nor damaged that I could tell. I don't recall doing any special testing for d4, and I wasn't doing any analog at the time, but the chip did whatever else I was doing normally.