Soundcloud -> @funkwhale
MeetUp -> @GetTogetherComm
LinkedIn -> @cloutstream
Google Calendar -> @calendar_social
Anything missing from the list? What else is needed?
@phoe is notabug.io federated using ActivityPub though? There are heaps of non-AP Reddit-a-likes, including lobste.rs, Hacker News, #SteemIt, #Minds, and others:
But AFAIK only the ones @switchingsocial listed are implementing AP