The Cotton Candy Computer [1] (link via Wlofie [2]) is an interesting computer in that it's a USB (Universal Serial Bus) sized computer. Granted, it's a bit more expensive than the Raspberry Pi [3] but the form factor is way smaller and could make (possibly) a decent environment for developing Android applications.
[1] http://www.fxitech.com/cotton-candy/what-is-it/