Hitec has a handy new device for LiPo users. The LiPo Checker shows percentage of charge and voltage of each cell. The device works with packs up to 6S and displays voltage to 0.01V. The LiPo Checker also has a balance function that can be used to balance the cells in a pack. The balancing current is 50mA. The LiPo Checker should be available for $19.99.
Learn more here.