City give aways

If I've had someone as a loyal ally all game, or if I've crushed an empire and suddenly feel sorry for them, or I've seen a nation ganged up on without mercy, I may gift them a city or even gold if I have it to spare.
Sometimes they make me regret helping them out though when they go and slag me off to the other leaders a handful of turns later.

Also, I sometimes put a civ in its place by giving him a city where he has none of the
terrain features that made him strong before I defeated him.
Sometimes I don't need or want their city and I don't want to raze it because the diplomacy goes nuts for that.

Do you guys give away cities or anything? Do you ever move civs around the map?

One tactic is to put a city in the middle of nowhere, gift it to a civ ur about to dow, then take all their other cities, essentially wiping them out without the diplo penalty.

I will frequently do this when playing big navy domination games (e.g. England or Ottomans). Snipe the cap to incapacitate the civ. As you have no land army you won't be able to keep the city from land forces, and you want to move on to the next target, so sell/gift it to a mutual friendly civ.