|This is a whole PC. ~$50 retail. WiFi and Bluetooth included.|
Or if you wanted to seed an area with wi-fi coverage you could make up a bunch of them and stick them on lamp posts. Use a Pringles can antenna for extra distance coverage and the can is the biggest part of the thing.
Put two of them miles apart and communicate via laser.
Detect deer in the back yard by radar and squirt water at them.
All kinds of things you want a PC for, you can do in a matchbox run off a 9V battery. For CHEAP.
Update: Welcome Rifleman's Journal readers! Consider building a bunch of these: Pirate Box. Never know when a little bit of anonymous file sharing capability might come in handy. Make it out of an Intel Edison and then tell EVERYBODY how you did it, I don't think its been done yet.