Personally, I can't knit. Nor can I crochet. I have skeins, needles, patterns, how-to books. I was just never able to pick it up.
I'm sure I COULD, but I have so many other hobbies that my house is a bit overrun with those supplies as it is, without becoming a yarn collector.
Still, I want to say HOW INCREDIBLY COOL recycled yarn is. I was recently doing a search for lace weight cashmere yarn (which can be pretty pricey), for a project I wanted to commission from my yarn-arts friend. While I was on Etsy I discovered recycled yarn! It had been unraveled from clothing, washed, and made back into a skein. And the people who do it seem to have a great knowledge of their products, naming the material, weight, and washing recommendations of the yarn.
Here is a great shop, called Crafty Yarn. I like how the yarns are separated by material. This is such a great way to reuse old clothing in styles that NO ONE wants to wear anymore. It makes me want to raid the Goodwill for sweaters to unravel!!