It's worth checking out fediservices.nz, who I'm mentioning not (just) because they are providing hosting for us here, but also because they run a bunch of fediverse sites, and their site just lists and links to them so it's easy to see what there is.
One I like is bookwyrm, a goodreads type site. There's an NZ instance at bookworm.nz (linked on the above site).
Other than mastodon, and perhaps the chat service Matrix, they are all pretty immature so expect bugs and not a lot of users.