Here is a collection of links to everything you could possibly want for Domino and HCL Notes (#LotusNotes)
I have many more links to add, so consider this a starting point and bookmark this one page for reference and return to it often.
Use this shortened URL that is easy to remember:
If you know of a link that I should add to this list, please post it in the comments and I will get it added.
If you find a link is broken, also let me know what the new link is or if it should be removed.

HCL websites
NEW!!! HCL Software Downloads Homepage: https://my.hcltechsw.com/
HCL Ambassador Program: https://www.hcltechsw.com/about/hcl-ambassadors
SoFy HCL and 3rd party software store and test drive sandbox https://hclsofy.com/

HCL Business Partner Registration: https://registration.hclpartnerconnect.com/general.nsf/welcome?open&login=1
HCL Business Partner Portal: https://www.hcltechsw.com/resources/partner-connect
HCL Idea Portal: https://domino-ideas.hcltechsw.com/ideas

HCL Customer Service- knowledgebase, documentation, forums, support tickets: https://support.hcltechsw.com/csm?id=csm_index
Your HCL Portal for personalized links: https://id.hcltechsw.com/app/UserHome
HCL Software downloads: https://hclsoftware.flexnetoperations.com/flexnet/operationsportal/startPage.do

HCL Domino Beta Program: https://registration.hclpartnerconnect.com/D11Beta
HCL Domino Volt Beta Program: https://help.hcltechsw.com/domino_volt/beta/welcome.html
HCL Domino Leap Complete Resources: https://hclwiki.atlassian.net/wiki/spaces/HDV/overview

HCLSoftware U: (the new academy) https://hclsoftwareu.hcltechsw.com/
HCL Software Blog: https://blog.hcltechsw.com/
HCL Sandboxes for Leap, Sametime, and Nomad Web: https://start.myhclsandbox.com/

HCL Notes/Domino Release Fixlist per release: https://ds-infolib.hcltechsw.com/ldd/fixlist.nsf
HCL Notes/Domno Release Schedule: https://ds_infolib.hcltechsw.com/ldd/fixlist.nsf/Progress?OpenView
HCL Open Source Repositories: https://opensource.hcltechsw.com/domino

HCL public Sametime Community: PENDING
HCL public Connections Community: PENDING
HCL Notes.net Domino Server for Notes client connections to resources: PENDING

Other resources
Planet Lotus Blog aggregator: https://planetlotus.org/
OpenNTF: https://www.openntf.org
Collaboration Today:  https://collaborationtoday.info/

3rd Party Software (Please tell them David Hablewitz sent you):
Crossware: https://crossware365.com/hcl-domino-email-signatures/
RPR Wyatt Vital Signs: https://rprwyatt.com/vitalsigns/
Panagenda: https://www.panagenda.com/
Ytria: https://www.ytria.com/ezsuite/
Maysoft SpamSentinel: http://maysoft.com/spamsentinel-for-hcl-domino.html
Libraesva https://www.libraesva.com/
Prominic: https://www.prominic.net
Belesoft: https://belsoft-collaboration.ch/en/

User groups:
CollabSphere: https://collabsphere.org
Engage: https://engage.ug/
C3UG: http://www.c3ug.ca/
DNUG: https://dnug.de/en/
Let’s Connect Nordics:  https://nordics.letsconnect.world/
sutol:  https://sutol.cz/
Spanish Domino User Group:  https://www.slug.es/

Social Media
Facebook Groups:
HCL Notes Domino App Store https://www.facebook.com/groups/domino.app.store
HCL Software – Digital Solutions Business Partners – Worldwide https://www.facebook.com/groups/135983955430
HCL Notes Domino Administrators https://www.facebook.com/groups/LotusDominoAdmins
HCL Notes Domino etc Enthusiasts https://www.facebook.com/groups/hclenthusiasts
HCL Notes Domino Developers https://www.facebook.com/groups/dominodev

Twitter
https://twitter.com/HCLAmbassadors  (2K followers)
https://twitter.com/HCLSoftware  (40K followers)
https://twitter.com/HCL_CollabSup  (1K followers)
https://twitter.com/HCLDigital  (47K followers)

LinkedIn pages
https://www.linkedin.com/company/hclsoftware/ (400K followers)
https://www.linkedin.com/company/hcltech/ (5.5M followers)

LinkedIn groups
Messaging & Collaboration Professionals – Lotus  https://www.linkedin.com/groups/37836/  (26K members)
HCL Domino, Notes & XPages  https://www.linkedin.com/groups/25044/  (10K members)

Youtube
https://www.youtube.com/c/HCLSoftware/videos
https://www.youtube.com/@HCLDigitalSolutions/videos
https://www.youtube.com/@OpenNTF