SimCity 3000 Plug-Ins* *link no longer existent. click here for archive mirror. -Includes landmarks and terrain/city maps.
SimCity 3000 Terrain Map Editor* -Saves Terrains as Paint files (BMP). Then you can load them using the method explained in the Terrain article.
SimCity 3000 Trainer (Mega Money Cheat)* -Trainer only works for version 1.0 of SimCity 3000. It won't work with the SimCity 3000 Patch.