The first Dragon soul I ever absorbed was while simply passing a robed npc while walking over a bridge, no dragon anywhere, not even in the water. That was a wtf moment.
The other memorable event was surviving a Draugr dungeon then almost getting killed as I exited by a falling Horker, thanks Bethesda.
i think we have a new expression thanks to bethesda, "its raining mamoths and horkers!" anyway, my story:
*beheads bandit*
bandit: tis just a scratch (or whatever that line was)
me: i killed you!
bandit: no, tis but a flesh wound
me: you have no head!!
bandit: yes i do, tis but a flesh wound