The iPad has excellent battery life but the more staying power the better, right? The Justin Ultra-Slim Power Case by Innovative Technology hides an 11,600-mAh rechargeable battery inside a synthetic leather cover. It can charge a full-size iPad up to two times -- or an iPhone or another smartphone up to seven times -- via its USB connector, the company says. The cover has a magnetic clasp to keep the iPad safe and secure when not in use. Priced around $70 online, the Justin Case weighs a little over two pounds, so you will have to endure the added heft of the portable battery.