If you have a spare pin you could attach an LED+resistor to show that the Arduino is still running, and if you have two spare pins you could use SoftwareSerial to send debug output to another Arduino which can relay the output back to your PC.
If you have a spare pin you could attach an LED+resistor to show that the Arduino is still running, and if you have two spare pins you could use SoftwareSerial to send debug output to another Arduino which can relay the output back to your PC.