Forget Minority Report and all that pointing and gesturing into the empty air like a demented windmill. The UI of the future is a small swarm of robots.
We usually think of robots as perhaps presenting a UI, but not as being a UI. Thumbles are small robots that drive around and interact with the user to create a dynamic physical UI.
The interaction part of the interface comes about by the user being able to grasp and move or orient the Thumbles and they in turn can move and rotate in response. If this all sounds a bit to abstract and specialized then the quickest way to see what it is all about is to watch the following video:
Thumbles make use of omniwheels which allows them to move in any direction without having to turn.
You can also see that to get the full UI out of a set of Thumbles you also need a projection system which might mean that the users hands get in the way . It looks pretty to have the UI projected on the hand, but it would probably be better to have a display surface below.
It is obvious that Thumbles occupy a niche in the UI world. I can't really see a Thumble-based text input device - but perhaps I'm not thinking creatively enough. It might be an interesting game trying to chase a runaway "key" just so you could type on it!
Given enough computational power plus a display on each Thumble, they could be useful in a wider range of situations other than games and discrete simulation.
James Patten, the inventor of the Thumbles, makes the interesting point that:
"Beyond gaming and data visualization, applications include video editing, command and control and logistics. There are a great deal of real-world problems that computers are not good at solving alone and people likewise have trouble solving, but people and computers working together using the right tools can solve very well. We believe that Thumbles are particularly well suited for these problems, particularly when teams of people must work together to develop a solution."
Being able to interact with a machine in a physical way to, say, work out a battle plan or a routing problem might very well have advantages. This is something that needs more investigation.