The Society for Psychical Research https://www.spr.ac.uk/
The Psi-Encyclopedia http://psi-encyclopedia.spr.ac.uk/
The Association for the Scientific Study of Anomalous Phenomena: http://www.assap.ac.uk/
Paranormal database UK http://www.paranormaldatabase.com/index.htm
http://itcvoices.org/ is the very best resource and analysis of ITC technology.
Historic archived texts etc.:
The Internet Sacred Text archive http://www.sacred-texts.com/index.htm for the Key of Solomon, Goetia, Qu’ran, Books of Moses, Havamal and many, many other historic texts. Invaluable for texts of antiquity.
Hermetics Library http://www.hermetics.org/library/Library_Grimoires.html is a great resource for Hermetic texts and study.
Twilit Grotto archives http://www.esotericarchives.com/esoteric.htm is another amazing source of texts from antiquity. If you need an ancient occult text, then it is likely here.
Occult Library https://occultlibrary.info/
Internet archive (massive resource for all things) https://archive.org/
Ancient Symbols resource: http://www.ancient-symbols.com/
The Mystica and Mythical Folk Encyclopedias: https://www.themystica.com/
http://www.tomegatherion.co.uk/home.htm A great guide to various aspects of the occult, groups and symbolism. Far from being the ultimate resource, it is however a comprehensive guide and launch pad.
http://www.ancient-symbols.com/ is a well researched and structured resource for all esoteric and religious symbolism.
Online magical sources:
http://www.quareia.com/#main is an incredible achievement. McCarthy here offers a complete, comprehensive and well structured course in magism. This course has the potential to take you from plebeian to adept if you have the will.
http://www.specularium.org/ An excellent source for the Chaos workings of Peter Carroll.
http://www.iotbritishisles.org/ Initiatory Chaos Magic group. Well structured and with a comprehensive approach.
http://www.lunarium.co.uk/calendar/universal.jsp for a lunar calendar.