An online electronics store for tinkering and learning, Adafruit, is selling bitcoin miner kits.
Mining bitcoins refers to the process of growing the crypto-currency's money supply: instead of a fiat currency where a central bank decides on how much money to print and distribute, bitcoins are earned when a computer, connected to a peer-to-peer network, solves a complex math problem.
Strong crytography is used to verify transactions. bitcoin is open source and fully decentralized. No one owns it.
With the growing interest in bitcoins, large and sophisticated computers are mining bitcoins. The Adafruit model, which uses a Raspberry Pi processor, is for hobbyists. It won't compete with the big boys.
But hey, it is cool looking and it may bring you a few dollars. A bitcoin is currently worth US$102.50, which would pay for the cost of Adafruit's miners kit.