Friend's first job was at the junkyard of a family friend, running a massive excavator and destroying cars. He said the boss was mostly in the office and turned the destruction part over to a handful of very young guys.
Also going out to job sites and demoing houses. He said the most fun part was the start: take a grab at the electrical panel and pull, and most of the wire in the house comes right out. And since that's most of the value in the house, your job is half done.
Incredible job for a 16-17 year-old