A lot of links and move details are archived on Figmentfly, though some things are presented as canon without specifying the sources. Press releases, studio statements, promotional materials and the actual canon often contradict each other. It's a great resource, but be aware than opinions on canon are presented as fact. Also, the people behind the site choose to ignore most transformative works and hope it'll all go aware if they ignore it hard enough.

Original Book:

Original Film:

Second Novel:

90s Reboot:

* Jet Car trailer
* Concept Art

Transformative fanworks:

* Buckaroo Banzai Deviant Art Group
There is more art on dA than is in this group, as creators need to approve being submitted to it. Some of the accounts with Buckaroo Banzai fan art are abandoned.
* Ao3 Tag

Communities:

* this Facebook group appears to be the spiritual successor to The Banzai Institute website.

World Watch 1:

* Issues collected on The Internet Archive

Fan Made Merch:

* At Society6
* At RedBubble