I've had my Arduino for a few months now, but today it has stopped working. It won't upload, the ATMEGA chip gets really hot to the touch (but no other parts), the L LED stays on unless I hold down the reset button, and only the RX LED flashes when I upload. Did I fry my board? 
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Arduino Uno with an ATMEGA32 chip. I simply had it plugged in when it failed, with a blank program loaded (nothing in the void setup or void loops, because I was about to start controlling a servo arm). Just the atmega gets hot, nothing else. And finally, I'm powering it through the USB cable.
You didn't plug the chip in back asswards in it's socket did you? It will go two ways, one way is interesting, the other way, just hot.
Lefty
You mean the ATMEGA chip? No, I haven't touched that thing. It's been working just fine as is for the last few months. 
If the chip is getting hot, it is likely damaged. There is no normal reason for it to be hot.
Remove the chip and verify your 5V supply is actually 5V. If it is, you'll need to get a new ATmega328.
Checked, it's definitely 5V. If I get a new chip, will I have to do anything or do I just slap it in?
CJRodgers:
Checked, it's definitely 5V. If I get a new chip, will I have to do anything or do I just slap it in?
It is a simple swap if you purchase a chip with the bootloader already burned on it.
Alright, thanks... I just hope nothing else went with it.