This computer's inventors see it as a means to an end: encouraging students to teach themselves how to program before they enter college. But the incredibly low price on this tiny and surprisingly powerful Linux-powered computer helped it land in the No. 18 position on our complete list. The perfect platform for hobbyists interested in building experimental projects, Raspberry Pi is like a digital blank slate. We dig the noble goal, but we also like tech toys, and this one is hard to beat.