I love this "conceptual knitting patterns" idea created by Lea Redmond. If I were still commuting via Bart, I would totally make this scarf on my travels. As it is, I'm tempted by the sky scarf - gather appropriately colored yarns, take a look at the day's sky, then knit 2 rows in the closest matching color. Repeat each day until the scarf is complete.
I have some yarns that would work for this already. Hmmm. Not, as I've said, that I need to start any more knitting projects.