Astrodienst, a treasure trove of services and resources: http://www.astro.com/
The Mountain Astrologer Magazine: http://mountainastrologer.com/tma/
Kepler College: http://www.kepler.edu/home/
NCGR, the National Council for Geocosmic Research: http://www.geocosmic.org/
AFAN, the Association for Astrological Networking: http://www.afan.org/
Astrology News Service: http://astrologynewsservice.com/
Astrolog 5.40 (free astrological software): http://www.astrolog.org/astrolog.htm
Sacred Texts: http://www.sacred-texts.com/