A character has been transformed (into an animal/plant/stone/whatever) and another character (or characters) must do some special thing to untransform them. And that thing should not be "fall in love with" or kiss.
(e.g.--I've just been reading some Grimms--in "The Gold Bird" the MC transforms a fox back into a prince by killing it and cutting off its head and feet; in "Jorinda and Jorindel", Jorindel must find a particular flower)
A character has been cursed to do something (wander/complete an unending task/whatever) and another character (or characters) must do something special to break the curse.
Suggestions, anyone? Any culture, any setting, it's all good. :) A title or a character name will do--I've got lots of books to page through, and good Google-fu if those fail me.