Be it musical, natural, mechanical; everyday sounds can be beautiful, or just hypnotic. In this thread, post your favorite sounds. This can range from nature, to musical instruments, to mechanical sounds, to man-made ones.
Here's a couple of mine:
Insects, including: Katydids calling on warm summer days and nights, and crickets
Frog calls, including the Spring Peeper and Gray Treefrog.
Birds: American Robin, Eastern Bluebird, Redwinged Blackbird, Phoebe, Mourning Dove, Woodthrush, House Sparrow, Canada Goose, Blue Jay, Cardinal, Common Loon, Bobwhite, Great Horned Owl, Lyrebird, Chuck Will's-Widow, Hermit Thrush
Airplanes going overhead.
AC hum of fluorescent lighting
Shortwave radio audio of atomic clocks
Yamaha CP-70 Electric Grand Piano
E-mu Systems Emulator II sampler
Prophet 10 synth
ARP 2600 and Quadra
Drum Machines: LinnDrum, Roland CR-78
Full string orchestra