Minecraft: (De-)Multiplexer design (3 bit MUX configuration)
Channel: WubbiConcepts
Date: 2012-03-10

This is the multiplexer that i used in my "color pixel" a while ago. It's based on lines of pistondriven AND gates, forming a device similar to a decoder. 
Also offers this design a usage as Demultiplexer (since this system just cuts off all wires which are going through except for one). Instead of the torches on the back just use a big OR gate (i thing you get what i mean).
You can easily expand this design to any number of bits, just build another version of this with a slightly different configuration of the blocks (note that in this video i show a 3 bit version with 2x3 rows. But it can be build in any way you like, the video is just an example).
Last feature this offers is the integrated memory. Since you push blocks arround the current state gets saved (just like a pistonbased RS NOR Latch).