Every hackers dream (certainly my dream, in any case) is a dozen of these chugging away quietly in the basement, in the living room, in the bathroom, in the car, in the bike... providing all the services that make living a thrill. What services, you ask. Let's see. Here's a few I can think of right away for my home use:-
-check the electrical devices not in use and switch them off
-optimize water use by throttling inlet at appropriate times (that means collect usage statistics and run an optimizing algorithm), and water the plants
-cache all data to reduce bandwidth use
-run custom applications (media format conversions, for a start)
A general purpose computational device that uses little energy, that we can mess around with, that can interface with storage and networks (wired or wireless). These devices enable a lot we can imagine. Even better, they enable a lot of things we can't imagine.