Interesting thread. Not that many for me:
Only departing:
SJJ - Sarajevo
CTU - Chengdu
Only arriving:
IAD
XIY - Xi'an
UII - Utila, Honduras
CUK - Caye Caulker, Belize
I've also flown "out of" and "into" the same airport on the same flight: BQH - Biggin Hill