Multi-color and variegated yarn
Multi-color yarn does the colorwork for you. This collection includes kettle-dyed Malabrigo Rios, Sock, and Rasta, Urth Yarns Monokrom, Lanaloft Handpainted, Burly Spun, Baah La Jolla, Feza Alp Premier, Euroflax multicolor linen, hand-dyed multi-color cotton, and recycled sari silk yarn and ribbon.
Getting the best look from multi-color yarn
Keep the stitch pattern simple. Stockinette, garter, seed stitch, and linen stitch let the color shine, while complex lace and cables can get lost. Variegated yarn can pool, which means colors stack up into blotches in certain widths. If you see it happening, change the stitch count, try a slip-stitch pattern, or alternate two skeins every couple of rows. Buy enough for your whole project at once, since hand-dyed colors can vary from batch to batch.
Want stripes without colorwork? Try self-striping yarn, or browse the full yarn collection.