What are some good knitting yarn conversion charts?

An easy to read, bare bones chart is available in the help section on ravelry.com. This is a comprehensive resource for most things fiber, including many free patterns for knitters and crochet buffs.

Yarn conversion charts for knitters ease the translation of yarn weights from the U.S. system, which uses descriptors like "lace," "worsted" and "sport" to the numeric system used to describe ply (2, 3, 4, 6) by the U.K, Australia and New Zealand. The best charts also include information about gauge, which is the number of stitches per inch that a certain weight of yarn should produce. It is always wise to check the gauge of your yarn before starting a knitting project by knitting a few rows and measuring.