This is fun. Garageband has a bunch of instrumental loops. This is a piano ballad. I doodled around on the harmonica on a separate track using the Blue Snowflake USB mic. I then mixed it down to a stereo mp3 file. Listen for our cockateil, Beaker, singing along with me.
Yesterday Apple announced Garageband for the iPad2. It will have Smart Instruments which will make this kind of recording even easier.