The XP1-Power is a little bulkier than your average USB cable, but it has good reason: it packs a back-up battery in-line. XMultiple have improved on their older version, now boasting 20 hours of extra juice and surge protection.
In addition to the surge protection, the XP1 is now compatible with several adapters that allow for the charging (and back-up juicing) of a variety of smartphones, MP3 players, GPS devices and the like. The adapters come at $4.99 a pop and the cable itself is $49.99. [XMultiple]