A Monthly Income Building in SimCity 4 is a special type of building that adds to the Monthly Income you get instead of Monthly Expense. Most people that are at the border line with Income and Expense may want to add these 5 buildings to increase the income your city will make. The 5 listed Monthly Income Buildings are listed below.
-Toxic Waste Dump
-Missle Silo/Launch Pad
If placing the Toxic Dump your area within the Toxic Waste is immediately radiated and you cant place buildings there (no houses wont be built). So its best to place the TWD outside the city, and might want to place some city-made trees instead of god-mode trees to hide it from public. Note also once placed the road that surrounds the building will be surrounded my NPC Sims protesting about the dump.
If placing the Army Base with the Missle Silo and or Federal Prison you may want to place some police stations nearby. Reason why if trying for the Military Copter mission there's an animation where an escaped convicted will hijack a tank and blow up the base and thus ending the mission.
If placing the missle silo by itself or in an Industrial Area and or near/next to a military base there will be some animation where the base will launch a missle into who-knows-where land. You can follow the missle until it vanishes off the map. On rare occasions the missle will explode in mid-air causing a Missle Debris Disaster. The debris from the exploded missle will fall over the area it exploded over. Depending on the height the missle debris will fall until it vanishes. If it is low altitude the missle debris will fall and destroy and flatten buildings creating semi-craters in the process and igniting buildings on fire.
The Area 5.1 base is a special base and its the only lot with a fighter jet and UFO (available in Rush Hour or Deluxe). This mission is all Vu, no Safety Mission or Medical Mission just 2 Evil Dr. Vu missions both will give good simoleons and giving you a bad rating for helping the Evil Doctor. As mentioned "What price of Agony do you want your city?" (estimated description saying)