Academia de Estudos Astrológicos a well-organised Portuguese site with some English content. The site represents their school and centre of Astrology in Lisbon teaching the Tradition.
Traditional

Robert Zoller has a good site with lots of information and downloadable articles in PDF format. A good looking, easy to follow site promoting his books, consultations and courses. Please note this URL has changed to www.robertezoller.com (please note the "e" in the middle of the name).
Medieval

Ruth Baker's Astrology gives information about Ruth herself and presents articles and horary judgements. Ruth's book is also available through her site.

Academia Astrologiae Homepage of the Academy for traditional astrology in Germany. Education, seminars and correspondence courses as well as a "colleagues forum" for professional astrologers. (English version to follow soon.)

Astrologia Restaurata The magazine for living traditional astrology (in German).

Chiron Verlag Germany's publishing house for astrology.

John Hayes Bookstore sells traditional astrological texts and features most of the titles required for the reading lists of the main traditional courses, including this one.

Triom is the site of the publishers of the Nativitas series of books by James Martin Harvey. This little-known, but important astrological researcher worked for years to obtain the birth data of hundreds of royal or well known people. The data and sources he provides are first class. The books cover the period from 1133 AD to modern times.

The site is in Portuguese, but contact Ruth Cunha Cintra (through the site) who speaks perfect English.

World Astrology a traditional site from Anton Grigoryev and Dorothy Kovach,. Russian and American astrologers. Good mundane articles. Downloadable software for accurate eclipse calculation and primary directions.
Traditional

http://mithras93.tripod.com/books/books.html free downloads of Christian Astrology (first two books) as MS Word 97 and 2000 files. For personal use only.

O Jardim Hermetico - an active and informative  Brazilian site

Aquarius Rising is Jonathon Clark's site. Full of forecasts, astrological information, articles.
Traditional

The English Merlin is a first class site with a great deal of information about William Lilly and the history of the English Civil War.
Traditio

The Astrology House site promotes and sells Janus astrological software which has an excellent traditional (and medieval) module. I use this software myself.
Software

FindAstrologer.Com a complete directory of professional astrologers, astrology courses, services and products.

Zodiasoft Technologies Astrology Software (was The Astrology X-Files Cabinet)  Investigation of mysterious astrological methods from ancient Greek and medieval sources.