A pair of memorable events for me; neither earthshaking...
Was pedalling my roadbike and found a small black box in the middle of a sidestreet. Stopped; it was a Radio Shack 10-channel hand-held scanner. Probably worth $50 when new. Put in batteries; it worked. I ordered a gizmo called a downconverter that picked up the 850 to 950 MHz range. At that time, analog cellphones used that range. By following directions, I could listen in to real-time telephone conversation; could not transmit. That was while I lived in Boston. I heard mostly business calls, some worth learning from, and some that are not fit for polite social conversation. In Colorado Springs, all calls I heard were boring; mostly building contractors. With all-digital cell phones now, I can't listen to any more good conversations.
Second... Was walking along a road outside Fort Huachuca in Sierra Vista, Arizona. Found a billfold of a soldier, ID, girl friend picture, two dollars cash, and his receipt for his M-16 rifle issue. I turned them into a former First Sergeant. He was pretty concerned about that rifle issue receipt. No reward; just knowing I helped out some soul that may have gotten into serious trouble without ID.