My most recent obsessive craft project for subway rides is this great crocheted shrug. It's so simple and you really only have to count out your chain stitch once and keep going and going until you get your desired length. This one was an easy 127 chain and then a single crochet until you reach X inches. For full details and free pattern download, go straight to Lion Brand Yarn and set up an account!
I'll keep you updated as this project progresses, but right now, i'm loving it!