Knotions Magazine
Great new online magazine for knitters. Knotions has a wealth of wonderful free patterns and articles for knitters to enjoy and of course knit.

Yarndex
A detailed listing of most of the more famous yarns available, including information on discontinued yarns and colorways. The yarndex list all of the yarn's information,including the content, yardage and weight, making it an invaluable research tool when substituting yarns for a particular pattern.

Ravelry
Online community for knitters and crocheters with some fantastic features. A great place to socialize with other knitters, admire finished projects and list your own FOs and WIPs. Ravelry requires you to apply for (free) membership, which is usually granted in a day or two.

YarnStandards.com
Standards and guidelines for knitting and crochet, including abbreviations and sizing/standard body measurements.

Knitting Pattern Central
Large directory of free knitting patterns, plus loads of other information.

School House Press
The knitting publishing house that was launched and made big by none other than Elizabeth Zimmerman. It is now run by her daughter, Meg Swansen and all of Elizabeth's books are in their catalogue.

Vogue Knitting Stitch Library
This part of the Vogue Knitting website lists some fantastic stitch patterns. They are sure to inspire designers and knitters alike!