Here's something that illustrates the sort of thing you can do in this game: a 12x5 LED display built in-game[1]. Reminded me of the Dwarf Fortress Computer[2].
[1] http://www.minecraftforum.net/viewtopic.php?f=35&t=24213
[2] http://www.geekosystem.com/dwarf-fortress-turing-machine-com...