These little pop-up iHome speakers output surprisingly good sound, are highly portable, and can plug into your mobile device or computer, which makes them ideal for traveling.
For example, at a hotel, I plug them into my iPhone at night and listen to radio stations while falling asleep using the wonderful TuneIn Radio app, which has a handy Sleep Time option to turn off at a specified number of minutes in the future. Since the iPhone is also plugged into the wall, it’s fully charged when I wake up.
The speakers recharge using a USB port, so upon arising, just unplug the iPhone and plug in the speakers to recharge them.
PS Soma FM Drone Zone plays fine music to fall asleep to.