The winner of this week's Android Arena was TaoMix, a relaxing sounds mixer. This app has several sounds to choose from including rain, thunder, traffic, birds, and more. Then you can mix them together, and even set how far away you want the sounds to be. It even can be set to move through the different soundscapes so the perspective will change as you listen.
Once you configure your soundscape the way you want it, you can save it for easy access later. There's also a timer that can be set, so you could use it to fall asleep. TaoMix has a very intuitive and easy to use interface, and is a great way to set your mood and relax.
TaoMix is free to use, and allows up to 3 sounds to be mixed together. There's a paid version that gives you access to more sounds, and allows you to mix up to 10 sounds simultaneously.