When Samsung came out with the K5 in 2006, we were stoked to see an MP3 player with an unusual design trait: a nifty built-in speaker that flipped out from behind the device and propped the player up for optimal listening. It helped, too, that the K5 offered plenty of features and stellar audio quality, though we weren't so keen on the super thick girth required to accommodate the speaker. Enter the S5, the K5's slimmer successor that adds built-in Bluetooth to the mix. While the S5 suffers from a few minor drawbacks, such as a small screen and proprietary video support, it's quite the worthy option for those with a penchant for top-notch audio quality and the capability to share tunes on the fly. Click the picture to launch the slide show, or click here to read the full review.