I want:
- Federated anime lists software - BookWyrm could be repurposed for this
- Torrent trackers - private trackers might be able to work by having each user have a ratio depending on their instance, tracker instances opting in to being viewable by other instances as a whole and/or users individually
- Booru-style image boards
- a Neopets clone
For my final wish, I want a Tiktok clone. I don't really know if this could work while maintaining any level of user privacy, as what makes Tiktok work so well is the sheer amount of personal user data they keep, from watch times to likes to reposts to shares to even knowing what videos you leave the platform on. I think a fediverse-style Tiktok clone would only be accepted if it only relied on likes and reposts for personal algorithms.
Edit: Oh, and good federated wiki software.