Speaking of gnomes, a while ago I brought back the Magic Manju (I think, the Martial arts one you find in China). He didn't really do anything after I stuck him on the front lawn, until perhaps a game week later when one of my sims wet themselves in the house. *Poof*. He teleports over the puddle (he likes to hover) and cleaned it up. I was hoping he would clean up all the puddles for me, but I guess it was a one time deal. Now he likes to teleport to places I don't want him (usually the backyard).
My witch-on-broomstick gnome is a bit easier to deal with. If I leave it alone long enough, it always seems to return to the shelf I put it on. Mostly it just changes poses.