WorldWrapper
This Spigot plugin enables a sort of cylindrical world model, suitable for use with "map" worlds based off the Earth, and such types of maps.
*Only entities being ridden or riding other entities will "wrap" (excluding players, who will always wrap).
Config
The WorldWrapper folder of your plugins folder (<server folder>/plugins/WorldWrapper) will contain a config file with settings to determine where each world boundary is, and which ways to wrap the world. Default settings are east-west wrapping only, with the world boundary at the current Minecraft world boundary of 30,000,000 blocks in each direction.