FlatGrass & CleanRoom maps
These are 2 blank maps that are each 1024x1024. They have no resources whatsoever, but they do spawn mobs.
FlatGrass: It's 63 layers of dirt then a layer of bedrock. Virus Total: Over 9000% Clean

CleanRoom: It has one layer of wool and one layer of bedrock beneath it. (Takes a hell of a long time to load.) VirusTotal

Instructions:
-Make a new world in Minecraft, then exit out of it.
-Navigate to your .minecraft\saves folder. (Run %appdata%, click on .minecraft, and go into the saves folder.)
-Open the .rar and move the map folder into the saves folder.
-Delete the folder of the world you just generated.
-Rename the map's folder to the world you just created. i.e. FlatGrass turns into World3
-Play Minecraft.
Isn't it redundant?