Stephanie, over at Glampyre Knits has a video tutorial on how to cut a tshirt and turn it into yarn. She’s also got an online class to teach you how to do this, finer points of the process and what to do with your creations once you’re finished.
Go here for Stephanie’s tutorial: http://www.glampyre.com/2010/03/17/two-new-free-patterns/
Not too long ago I did a test knit for another designer that was for a cabled cardigan. It’s really cozy and nice but it just about broke me in a ton of different ways. I couldn’t get gauge, which I suppose is my own problem, but mainly I was somehow both bored and forced to pay attention at the same time.
Love this! (As well as the idea of using old T-shirts for Swiffer covers. That’s never crossed my mind!) We made a little throw rug out of T-shirts using the same technique (http://bit.ly/atgzsH) recently, but love the idea of dying them with coffee as well. In any case, thank you for the link, this is really cool.