I charge mine every night on a dock by my bed, running Alarm Clock Pro:
http://itunes.apple.com/gb/app/alarm-clock-pro/id335678373?mt=8
If the battery is running low during the day, like when I'm streaming music for hours at a time, then I plug it into my laptop.
http://itunes.apple.com/gb/app/alarm-clock-pro/id335678373?mt=8
If the battery is running low during the day, like when I'm streaming music for hours at a time, then I plug it into my laptop.