At Killer Bee's website, there are two map files of the Earth. These maps were previously made by fans of the game.
From Empire Deluxe Internet Edition, there is Big Earth (author unknown to me)
From Empire Deluxe Enhanced Edition, there is the larger Thoba's Earth
These maps can be downloaded, along with the convertor that made them, at
http://killerbeesoftware.com/edce/code/maps
Now, for diehard Steam players, before you say "Steam Has A Workshop!" this is already known, but that has not been implemented into the game at this time. But these maps are so fun and interesting to play on, I wanted to go ahead and share.
To install the maps, you need to extract them into the /maps directory. You can locate you by looking in the Administration Screen (Administration Button in the Main Menu) and pressing the "Directories" button.
If you have maps (or any other game creations/modifications) you would like to share, please post them up somewhere and drop us a line in the forums. Or if you have no where to put it, feel free to wrap it in a zip with a short read me and I will try to come around and post it in my area.
--Mark