eMachineShop.com is a site which offers rapid prototyping and machining of customer designed parts. They have a 3d CAD application that customers download, then use locally to design the part they wish to have produced. Once the design is finalized, the client uploads the design to the website from the CAD software. eMachineShop.com then produces the custom part and ships it to the customer.
This is the future of interactive web services. Amazing.
They have a sister site at www.pad2pad.com which offers the same sort of service for circuit boards as well.
Update by Scott:
A friend of mine here in Atlanta, Simon Arthur, started a similar site called Big Blue Saw. Check them out.