1) A flight of five F-15 Eagles lining up for a picture behind the refuelling tanker (I was in the boom ops blister talking to the lead over the radio, and yes I did ask if they could close up a little ;-) )
2) A storm lighting up the clouds over Rwanda on a recent LHR-JNB trip
3) Standing with my toes over the ramp on a C-130 photographing The Red Devils as they jumped off past me.
4) Hudson Bay frozen solid seen from a otherwise very tedious LHR-SFO flight.
5) People eating dinner in their apartments just off (it seemed) the wingtip on final into Kai Tak.
I'm sure there are more.