Mid America Dharma: Offering insight meditation to the Heartland. Check out their local retreats and sitting groups.
Dharma Seed: Freely offering Western Buddhist Vipasanna teachings by download, CD, or cassette
Insight Meditation Society: Retreat center founded in 1975 with guiding teachers Sharon Salzberg and Joseph Goldstein, located in Barre, MA.
Spirit Rock Meditation Center: Retreat center located in Woodacre, CA and founded by Jack Kornfield.