A useful little collection of events involving the City Watch to use at intervals when the party is visiting any settlement large enough to have regular Watch patrols of some kind. Many of the encounters could be developed into complete mini-adventures, or have ramifications that repeat for as long as they stay in town (or even if they come back again).
The work begins with a straightforward 'Encounter Chart' which makes use of several D6 rolls to determine what the Watchmen the party meets are doing - anything from asking questions to demanding something. Each chart has a subchart, so if you roll that they are asking questions you roll again to determine what the questions are about. There is also a table to determine what happens if the characters cannot or will not provide what the Watch are after
If your initial roll is a 6, there are 20 more detailed encounters. These are the real fun elements and more likely to develop into side-adventures of their own.
Naturally, you can choose rather than roll dice, and make the encounter a planned event rather than a random one if that suits your needs better. Most parties are at least wary of the authorities so the potential for some fun is always there...