Some links in no specific order
https://easyeda.com/jeroen1328 my easyeda project page
https://commodore.hcc.nl/ (Dutch)
http://www.forum64.de/ (German)
http://www.lemon64.com/
http://aminet.net/
http://amiga.cafe/ (Dutch amigascene)
http://www.worldofspectrum.org/
http://www.commodore-news.com/ (Weekly Commodore news)
https://commodore.bombjack.org/ (good source of commodore books)
https://www.pictorial64.com/(images of C64 problems and the possible responsible chip)
https://portcommodore.com/rcarlsen/cbm (Good source of commodore (repair) information
https://www.protovision.games/ (webshop for c64 related hardware and software)