Collections of Nostr things:

Index Nostr App: https://www.nostrapps.com/

Open Source tag | Nostrich.fun | Superguide https://nostrich.fun/?tags=open%20source

Discover Clients, Guide of NIPS: https://nostr-ings.com/docs/index.html

Nosdav suite of tools: https://nosdav.com/

nbd-wtf/nostr-tools: Tools for developing Nostr clients: https://github.com/nbd-wtf/nostr-tools

Bevstr-Nostr: https://www.bevstr.com/Nostr/

scrapbox: https://scrapbox.io/nostr/

nostr Community Group: https://www.w3.org/community/nostr/

Nostr Japan: https://github.com/nostr-jp