I had one about 3 1/2 years ago. I was flying a traffic watch C-172. It was about 6am and still completely dark out. I had just taken off from KLEX with two radio station reporters and myself aboard. I had just started my crosswind turn at about 650AGL when the engine began to run very rough, and then quit.
I quickly turned back toward the runway and notified the tower who cleared me for landing on any runway. Unfortunately there was an airline turboprop getting ready to take off on the same runway and when the tower controller cancelled his takeoff clearance, the pilot replied "Okay, cleared for takeoff" and began his takeoff roll.
Now I couldn't land in front of the turboprop that was rolling down the runway, so I elected to go behind the airplane. The tower controller ordered the airliner to abort his takeoff roll, and I told him over the radio to continue taxiiing down the runway as I needed room to land behind him. He continued down the runway and I landed a couple hundred feet behind them on the same runway.
The mechanic found a faulty spark plug that had exploded in the cylinder and locked up part of the engine.