The neural interface can be put in your armour slot and interacted with like a computer. Modules and other peripherals mounted on it get full access to the player.
Plethora comes with several other modules which allow interacting with the world
You can fire lasers
You can attach the neural interface to mobs too: and control their movement.
Squid with frickin' laser beams attached to their heads!
All modules have an in-game use too.
