Tylt PowerPlant

Flip down the Tylt's front flap to expose its USB port and swinging arm – the arm can be customized with a 30-pin or micro USB, making it useful for older phones or MP3 players you may still be using. The PowerPlant's battery, the biggest of the group, refueled a depleted tablet on one charge, but its build quality left something to be desired: Its arm made charging devices awkward, and the flap fell off our test unit. Still, the lime and black color combination is nice to look at, and its distinctive flap design ensures that it closes up nicely, making it handy for travel. [$60; sprint.com]