Yesterday, I was flying mostly off-shore (Atlantic Ocean off NJ Coast) and in some of the larger bay areas (Chesapeake Bay and Delaware Bay). Anyway, I was on the way back in - about a mile off the beach heading for an inlet when a fixed-wing plane missed me by about 50-75 feet!
I was decending for a low pass along some boats and was about 100' ASL at the time (getting set up to take some pictures). The nearest air field was about 8 nm away or so. He was heading into the sun, so I don't think he ever saw me. The weather and visibility were excellent, and he looked like he was following along the beach at low-level. From my perspective, he came out of nowhere and cut right in front of me before I knew he was there!
Needless, to say I was a bit pi$$ed off that this bone-head was flying below 500' and didn't make any position calls. More importantly, he didn't pay attention to our position calls. What the heck was this guy doing at that altitude?

Has this ever happened to you?