ComputerCraft

ComputerCraft is a mod that adds Computers and Turtles, which can be programmed with the | LUA language and come with some programs to get the player started. Computers and Turtles can also interface with various peripherals as well as redstone dust, red alloy wire, and bundled cable allowing for many advanced uses.

Getting Started with ComputerCraft
If you're new to the mod check out the Getting Started with ComputerCraft Guide