You don't need much more than your MP3 player--whether it's a standalone device or an app built into your cell phone--to enjoy all your favorite tunes on the go, but certain accessories can up the entertainment factor.
For example, if you spend a lot of time in hotel rooms, a portable speaker is practically a necessity, allowing you to rock out without being tethered to your headphones. In fact, why not do away with the wires entirely? One of the more advanced features you can find in portable speakers on the market today is built-in Bluetooth technology. This wireless protocol lets you stream music from any device with integrated A2DP technology, which can be found in most media-centric cell phones (save the iPhone) and even a handful of dedicated MP3 players.
The speakers often include integrated keys for controlling music playback, and some even offer mics for use as a speakerphone--and, really, we see no reason not to kill two birds with one stone.