Wilderness Dharma Center - meditation and leadership training in Nature
Online Dharma Talks - excellent collection of teachings available in both real-time streaming and MP3 formats
Access to Insight - excellent and extensive teachings from the Pali Canon and other sources from the Theravadan tradition
Dharma Seed Tape Library - huge collection of dharma talks on tape and CD, many offered through dana
Dharma Stream - another valuable collection of dharma talks
Insight Meditation Society - sister center to Spirit Rock, located in Barre, MA
IMS/BCBS Links - nice collection of annotated links maintained by IMS and BCBS
Community of Mindful Living - central website for practice in tradition of Thich Nhat Hanh
SRMC Links - links maintained by Spirit Rock Meditation Center
Worldwide Buddhist Directory - large list of meditation centers and temples