Eltima Software has released Elsehwere: Ambient Nature Sounds for the Mac. It requires Mac OS X 10.6 or higher, costs US$0.99 and is available at the Mac App Store.
Elsewhere randomly generates the environmental sounds helping you either to concentrate or relax depending on the choice of the atmosphere. You can adjust the volume, and switch between day and night sound modes. The sounds are random ,imitating the rhythm of real nature sounds.
Elsewhere 1.0 offers three environments: Beach, Forest, and City. More ambients will be added in future releases. Elsewhere automatically switches between day and night depending on your time zone, but it’s possible to switch between day and night manually when needed.