Today only, Griffin Technology takes 25% off sitewide with no minimum purchase required via coupon code "WINNER25". Plus, all orders net free shipping. Combined, that's the best percent-off deal we've seen from this merchant in more than three years. (We saw 25% off in May; however, it required a $10 minimum to net free shipping.) Griffin sells accessories for iPhone, iPod, iPad, tablets, Microsoft Zune, and more.

A best bet is the AirCurve Play Acoustic Amplifier for Apple iPhone 4 (pictured) for $19.99 before the above coupon, $14.99 after. With free shipping, that's the lowest total price we could find by a buck. This item amplifies the iPhone speaker without batteries or electricity.