iDuple of India recently announced that they are working on an Internet tablet with just a single app. A Web browser. There’s no hard drive, so a fast boot up should be no problem. It will remotely connect to a server that runs a virtual operating system.
Of course you can still run apps and perform various tasks, but you will need to remain connected to the server at all times. Not great if you are traveling in places where internet connectivity isn’t so heavy. Still, it’s an interesting take on a tablet.