Build houses that spawn autonomous lumberjacks, link them to outposts for work areas, and power the network in single-player or multiplayer.
Mods introducing new content into the game.
Augmented or new ways of transporting materials - belts, inserters, pipes!
Map generation and terrain modification.
New Ores and resources as well as machines.
Related to roboports and logistic robots.
More than just chests.