In addition to law enforcement, I listen to whatever my antennas can grab out of the air, mostly all at the same time, from local and nearby jurisdictions. I live in a high location, so I have a good-sized coverage area. Analog, DMR, NXDN, P25, conventional, trunked, various bands.
Aero - unallocated airspace ch, air search and rescue, local light-plane flight corridors, military.
Airports - tower and ground traffic, airport fire dept, airport security, the rare crash.
Amateur - local and linked repeaters/systems.
Ambulance - emergencies, motor vehicle accidents, disasters, air-to-ground with rescue crews and hospitals.
Emergency Preparedness - Regional emergency repeaters and simplex, for earthquakes, tsunamis, etc.
Coast Guard - marine search and rescue, assist and distress calls, patrols.
Electric Utility - power line repair during/after storms and power outages.
Environment - oil-spill clean-up, pollution patrol (via aerial surveillance).
Fire - fires, motor vehicle accidents, high-angle rescues, swift-water rescues, disasters.
Fisheries - surveillance, enforcement.
Forestry - wilderness patrols, wildfire fighting, interface fires.
HF - Amateur, shortwave, whatever I can find.
Highways - traffic and road conditions, snow-plow activity.
Industry - large mines and other industrial entities.
News Media - air-to-ground and other channels.
Public Works - snow-plow activity, bylaw enforcement.
Prisons - general traffic, occasional disturbances.
Search and Rescue - searches, wilderness vehicle extrication calls in areas not covered by city fire depts, heavy urban search and rescue.
Security - hospitals, malls, large infrastructure projects.
Ski hills - ski patrol, search and rescue.
Tow trucks - monitor dispatches for locations of motor vehicle accidents (to avoid).
Trucking - highway chatter for traffic and road conditions, logging roads.
There are other entities of course. Not everything gets published on the Internet, so that we can continue to monitor them without them getting wise to the fact.