Simple LiPo single-cell charger from Sparkfun, with a Micro-USB cable connector.
We're using more LiPo cells in our projects at Solarbotics all the time, and this little, basic LiPo charger from SparkFun is finding use here. Designed to charge a 3.7V LiPo at up to 500mA (the current limit of traditional USB ports), it's a plug-in-and-go solution.
The board features a status LED, JST connector for your battery (JST-type used in the batteries we carry), and a micro-USB connector, plus a mounting hole for a more permanent installation.
Make sure your battery's connector wires match the polarity shown on the charger. Red = +, Black = -. If your battery doesn't match, you can easily pry up the tabs that lock the pin into the connector, and swap their positions so they match the charger's polarity.