Another, less-frequently mentioned one is the woman in the house on Route 217 in Platinum. On the first time that you talk to her, she gives you a Spell Tag. Then, if you exit and re-enter her house, you find it completely empty, with the old woman having vanished.
Oh yes, the yuki-onna. Tbh while I appreciate the ghosts, since they don't really do anything, I have a hard time remembering them or caring for them in general. The ghost girl in Phoebe's chair is memorable and creepy though.