If you thought cubes were so last-century, take a look at this Yamaha NX-A01 portable cube speaker that's just 3.3 inches high. It uses an optional Yamaha Bluetooth receiver to let you listen to wireless audio from cell phones or PCs, and it's punching plenty of power for its size, driving 4 watts each into two channels. It's $129, and its TRX-RO1BT Bluetooth receiver is also $129.
This is one great-looking speaker, and weighing 11 ounces, it's packing some serious magnets inside. The company quotes a frequency response of 90 Hz to 20 kHz, and if it's anywhere near that number, it'll sound sweet. Too bad that pricey Bluetooth receiver isn't internal or included.