Ok, so this may not exactly be a safety specific issue but... I guess I learned my lesson and need to start calling the Dig Safe people before I putter around out on the property.
I picked up a 5' scraper blade today and decided to play a bit. I was dragging it around in an area I plan to turn into a small orchard and after an hour of moving dirt around I realized that there was a 45' long piece of coax cable floating around. I went into the house and sure enough, I had dug up the cable TV lead into the house from the street.
All my utilities are buried between the street and the house and, silly me, I just assumed they'd be buried more than 3" deep. I guess that was a bad assumption. Luckily it was just cable TV. It could have been the main 200 amp electrical service into the house. Lesson learned!
So yeah, if you're gonna start digging, make sure the area is clear of utilities - wires, pipes, whatever... Better safe than sorry.