I just stumbled across the My Recycled Bags blog. It's a great site that includes instructions for making your own plastic bag yarn (called plarn) and creating lots of useful items like water bottle totes, reusable lunch bags, purses, etc. There's even Barbie doll clothes crocheted from cassette tape!
The author of the blog is too modest to tell us who she is, but kudos to her for giving us such a great resource! Here's a pick of her latest Barbie fashion.