Okay, so this one's not exactly a smartphone accessories—it's an application. It's also, however, one of the most useless, yet amusing, mobile apps on the market. Available via Apple's App Store, iBeer is exactly what it looks like: A program that simulates drinking a nice, foamy ale and turns the iPhone into a rather pricey pint glass. And because the iPhone's accelerometer detects motion, the "beer" swishes back and forth as the iPhone moves and drains when it's tipped upside down. iMilk and iWater are also available for underage iPhoners.