Tow trucks sometimes can be interesting, but I actually find the local public school bus channels a good monitoring activity.
In larger school districts, the public school bus frequencies are actually interesting.
I mainly listen for traffic and road conditions. Since many of the buses start out as early as 5 or 5:30 am you can get a good idea of what the overall road conditions are. During the Winter months you can get an exact idea of where the road conditions are going from driveable to dangerous. Even on evenings and weekends the buses for sports and after school activities come in handy as well.
Then add in the drama of the fights on the buses, the crazy parents and other fun stuff like missing kids, kids that got off at the wrong stop or even the missing lunch bag or instrument throughout the day.
While my kids were in school I often found out when school was closed or delayed by listening to the school bus channels before there was an official announcement.
I have also occasionally been made aware of a missed major event when school buses were dispatched to corral people and move them to a safer location.