http://en.wikipedia.org/wiki/Yoga
Read all about Yoga in Wikipedia

http://www.yogajournal.com/
Website about Yoga poses, meditation, Life

http://www.yoga.com/
Learn where to buy equipment (clothes, mats, etc.), books, videos, etc. about yoga

http://www.yogasite.com/
Website about equipment, DVDs, wholesales, etc. about yoga