@J12t@social.coop A few really unique ones:

* Dokieli - Some kind of wiki-like page thing?
* reel2bits - Defunct, I think, but basically demonstrated a way to do federated Soundcloud?
* CastoPod - a podcasting platform
* ActivityPods - a combined ActivityPub server / SoliD Pod
* Pinetta - a Pinterest clone?
* Vocata - a vocabulary-agnostic ActivityPub server that just takes whatever you throw at it.