Tekkit

You can download Tekkit from here.

Tekkit is Minecraft with mods suitable for engineer's mindset. The mods provide concepts such as electricity, complex processing machines and connecting these machines to create even more complex systems. The windows installer might not work, use the Linux/jar instead and launch it from command line with 'java -jar technic-launcher-latest.jar' or modify a shortcut link. Also you'll need minecraft_1.2.5.jar copied to %appdata%\.techniclauncher\cache folder.

The Tekkit server can be found from siegbahn.dy.fi