At Biggin Hill in the mid 70s I saw a Bell Jetranger (doing pleasure flights) take-off into the underside of a landing Tiger Moth.
The T-34C at Mildenhall
The 'Vintage Pair' at Mildenhall
The Italian G-91 at Mildenhall (it came down at the edge of a camp-site where we were camping for the weekend, and we made a few trips down to visit the 'guard airman' that evening to keep him supplied with beers and hot food).
The MiG 29s at Fairford
The G-222 at Fairford
A hot-air balloon at Fairford; very soon after lift-off (evening launch), it drifted across the car-park at low-level, and came down on top of a car - does that one count?
The Sukhoi at Paris in the late 90s. (Not sure if this one counts, we were several miles away at our hotel, watching the display from the balcony; I went back into the room to get another beer, heard a shout, came out and saw the plume of smoke).