Cat Tracking (long side quest idea)
Here's one for you DM's that want a campaign long side quest that the players will get done absentmindedly. The players are asked by a local animal sanctuary that there cat section had been unlocked by a rouge druid. They ask the players to return any they find on there journey. Any cat found & then return earns the player a little bit of money & experience. Implement this by just having one of the cats appear every so often, in places cats really shouldn't be.