Knitters/crocheters!
This website is awesome!
http://customyarn.com/ It's the lastest version of the custom yarn builder from Yarnia, Inc, which is a yarn store in Portland, OR that I like. (I have worked online with the owner before, and I've visited the shop while in the area.) It is awesome and intuitive and makes fantastic yarn.
It's still in beta, so give feedback here:
sales@yarniapdx.com