We mean it when we say it: Mophie's Juice Pack Air for iPod touch 4G ($50) is the company's best-looking and most reasonably priced battery pack yet. Like all of the company's other Juice Packs, this is designed as a case that presumably will only fit the single iPod touch 4G model -- possibly a sequel if it keeps the same form factor -- and has a thin rechargeable battery built into the back. Soft touch rubber is used as a coating for the hard plastic…
