NOAA
Noaa: Pmel: Acoustic Monitoring, Bioacoustics
Outlines the National Marine Mammal Laboratory's project studying whale acoustics (the sounds whales make). Links to clear acoustics tutorial. Also includes whale biology, with acoustic descriptions and sound clips of their calls. Very...
Oakland Museum of California
Listening to Nature: A Sound Walk Across California
Terrific site with a wide variety of animal sounds, accompanied by species specific information.
Other
The Virtual Bird: Birdsounds
This site contains a number of sounds files with birdsongs of many different types of birds.