A new web site called "Teach Astronomy" (http://www.teachastronomy.com) has been created to serve astronomy instructors and their students, amateur astronomers, and members of the public interested in astronomy. The content includes an online textbook of 400,000 words and 1200 images, 40, 000 articles from "Wikipedia," over 1100 video clips covering all topics in astronomy, over 6300 images from "Astronomy Picture of the Day" and "AstroPix," over 1400 podcasts from "365 Days of Astronomy," and 25-30 astronomy news stories each week from "Science Daily." All these resources are navigable by a keyword search and via a unique visual interface called a Wikimap, which presents the items clustered by degree of keyword overlap and allows surfing among related items. The site can serve as a replacement for a textbook and as an information resource for formal and informal learners. Future development includes building an instructor and learner community and creating homework assignments that utilize different content areas within "Teach Astronomy." (Contains 5 figures.)