An image is worth a thousand words. This is the single reason why Garage Band is so cool:

Garage Band isn't great because of new technology, or ease of use, or interface design (perhaps in spite of wood grain...). It's great because it gives me a chance/reason to break of the rut of being just a consumer of music. I can dabble on the creative side, even though I couldn't play in instrument to save my life.
It's not exactly art, but that's my first piece of music that I could actually put my name on. In iTunes.
An extremely simple song, started on a flight from SFO to SeaTac, and finished in about 15 minutes this afternoon.
Look at me! I'm a musician! Howdy howdy howdy!
Here's a link to the output file. It's still quite rough, and shows a profound lack of musical taste or ability, but still...