Redstone Elevator which almost reaches the clouds. I'm leaving room for an area which I'll call the Boss Suit. Maybe it's cheesy sounding but it will serve as a tower that oversees the rest of the redstone powered machines.(and non-redstone-powered "machines")
The first working machine is an infinite cobblestone machine. If pistons could destroy other blocks, then I could make a completely automatic one but unfortunately Notch didn't make it that way.
I wish he would make pistons with the ability to destroy other blocks, providing they're made with Obsidian push plates rather than wood. That'd be cool.