There are soothing sounds galore, including rain, waves, crickets, wind chimes and bird chirps, but sometimes white noise can be the most uncomplicated and relaxing. Launched last month, the S-100 White Noise Machine by Sound Oasis offers 10 white noise tones in a compact, portable design that also doubles as a speaker, should you wish to play sleep-inducing music with your mobile device. $59.99 at sound-oasis.com.