general

• calendar sharing (caldav)
• filesharing
• webmail (imap client)
• notes (sync between desktop/mobile/web)
• video conf & chat → https://apps.nextcloud.com/apps/spreed
• federation (w. other nexclouds)

specific

• “find my iphone” (AAPL) → https://apps.nextcloud.com/apps/phonetrack
• polls (e.g doodle, loomio, etc) → https://apps.nextcloud.com/apps/polls

etc

• etc+