I just got the Fall 2006 issue of Spin-Off magazine, and it has the COOLEST article about dyeing yarn.
Here's what you do: You knit all your spun yarn with a knitting machine to make a big rectangle, then you dye stripes on the finished fabric.
Then, when you are completely satisfied with it, you can unravel it, and make anything you want. Easy Self-Striping yarn!
I am really excited about trying this. I got a knitting machine at a thrift store about 2 years ago, and it's just been sitting around. Now, I can put it to work!