A collection of important sources of information for enthusiasts:

Websites

Link Description
https://thinkwiki.de/ German ThinkWiki
https://thinkwiki.org/ International ThinkWiki
https://download.lenovo.com/eol/ Lenovo End Of Life Portal
https://download.lenovo.com/lenovo/content/ddfm/T23.html driver page; replace T23 with desired model
https://tp.krelay.de/ ThinkPad Type Search Engine
https://thinkpads.com/support/hmm/thinkpad-hmm.html ThinkPad Hardware Maintenance Mmanual Collection
https://www.701c.org/ Information about the restuaration of the 701c (also interesting for other models)
https://www.elhvb.com/mobokive/eprm/eprm2/f3200.htm Electronic Pocket Reference Manual, utility for IBM staff

Media

Link Description
YouTube: Laptop Retrospective The channel about ThinkPads and History
YouTube: This Does Not Compute Retro Computing channel, occasionally reports about ThinkPads
YouTube: Psivewri Retro Computing channel, frequently reports about ThinkPads

Tools

Link Description
thinkpad_driver_downloader Tool for downloading ThinkPad drivers more easily