Here is a brief - and not necessarily representative - selection of links.

JJ Crowder Masonic pages are particularly good.
Pietre-stones An enormous site, packed with information. A clear and comprehensive attempt to rebut objections raised by the 'Anti-Masonry' movement.
Freemasonry Watch The most well known of the 'Anti-masonry' sites. Apparently there have been several attempts by Freemasons to close this site down.

Vernon Jenkins was the great pioneer of Biblical gematria in recent times. His discoveries were awe-inspiring and profoundly important. Unfortunately, he passed away in late 2020 and his website is no longer available. However, some of his key papers are available on the Academia website. There are also papers on this site.
Cnaan Aviv has an interesting site on gematria that includes an extremely useful calculator. It calculates Latin script words by Agrippa's gematria code, although he curiously calls this 'Jewish Gematria'. His calculator also produces figures for 'English' and 'Simple' gematria, but these are modern versions without historical provenance.

Ros Barber is the author of the acclaimed blank verse novel The Marlowe Papers, which explores the Shakespearean afterlife of the poet. See her research output at her official Goldsmiths University profile.
Robert U. Ayres - a distinguished professor of economics - has written a book supporting my research findings: On the Authorship Controversy: Evidence That Christopher Marlowe Wrote the Poems and Plays of William Shakespeare. Professor Ayres rather curiously added me as a co-author of the book, but I only became aware of it five years after its publication. Apparently, he was unable to track me down and believed I had died. I have not yet had the opportunity to read it, but I am sure it is good. Unfortunately, the book is prohibitively priced for the average reader.
The Marlowe-Shakespeare Connection A great resource for new research on the Marlovian theory, edited by Carlo DiNota and featuring outstanding contributors. Unfortunately, it is no longer active.
Peter Farey Peter's website has been an excellent resource containing his own impressive research and a lot of extremely useful documentary material too. Sadly, Peter passed away in January 2020. This is now a legacy site that is being kindly hosted by the International Marlowe-Shakespeare Society.
Donna Murphy Author of several books, including: The Marlowe-Shakespeare Continuum: Christopher Marlowe and the Authorship of Early Shakespeare & Anonymous Plays.
Daryl Pinksen Daryl is the author of Marlowe’s Ghost: The Blacklisting of the Man Who Was Shakespeare
Samuel L Blumenfeld The late Samuel Blumenfeld wrote The Marlowe-Shakespeare Connection - A new study of the authorship question
The International Marlowe-Shakespeare Society This is the best overall source for information about Marlowe and his relationship to Shakespeare on the Internet. The Society and its website were created in August 2009 by an informal group of supporters of Marlowe's candidacy for the authorship of Shakespeare's work. They include(d) Peter Farey - Carlo DiNota - Isabel Gortazar - Daryl Pinksen - Mike Rubbo - Sam Blumenfeld.
The Marlowe Society The Marlowe Society is dedicated to preserving the memory of the greatest poet and dramatist prior to Shakespeare. Some members believe Marlowe was Shakespeare, too. There are interesting research articles and links, as well as full information about the society.
PBS frontline The American TV channel's site that sprang up out of interest in Mike Rubbo's film. Lot's of information here and especially useful for educators trying to make Shakespeare interesting for schoolchildren.
Matthew G. Scarsbrook Matthew is an up and coming young screenwriter and novelist who has recently written a very interesting account of Shakespeare's role in Marlowe's last days.

Shakespeare Authorship
Alan Green has made a great many amazing discoveries of esoteric knowledge coded into Shakespeare's Sonnets and the First Folio. His dynamic website is full of fascinating information. His Youtube channel Bard Code is compulsory viewing for anyone interested in a deep dive into 'The real Shakespeare. I made an appearance in epidode 11. Alan knows more about the Rosicrucian mysteries of Shakespeare than anyone else out there - period.
Diana Price has a site accompanying her excellent book Shakespeare's Unorthodox Biography - New Evidence of an Authorship Problem.
The Shakespearean Authorship Trust has great resources and many fine videos on its YouTube channel. Membership is well worth a trial.