Here is a demonstration of my Fully Automatic Cobblestone Generator!
With the new Minecraft snapshot 12w36a came the new mob Wither! You can trap him in a 3x3 area and when he takes damage he will destroy all the blocks in that 3x3 area. Using this knowledge i created a massive Cobblestone Farm that produces over 100,000 Cobblestone Per Hour!
This farm is 100% my design but the idea has already been shown on youtube, i simply improved upon it.