This a cobblestone generator station.

There a unlimited water source and a lava source. I had to use a command block because there is no way to make a unlimited lava source. Damn you mojang. It should work like water. There are shut offs for water and lava. This machine make cobblestone without losing any.

I added the mcedit schematic. Feel free to use. Just give me credit if you use it in a map and leave all the signs on it.