HackMD.io - realtime markdown collaboration
HackMD is a great tool for realtime markdown collaboration. Visit https://hackmd.io/new will create a new note for collaboration. Then Gather can use this url for the entire session.
Trello is a project management application, and at least viewing the frames would be very interesting. when I put the URL of Trello it doesn't load anything.
Plink - Shared music-making
Another great music option, different from the Chrome Music Lab shared piano. Super easy to use, with interesting sounds, and the pentatonic scale guarantees that everyone sounds boss. If you embed the URL of a private Plink room, then the object will take you to that shared private room right away, no fuss with codes or passwords.
Guestbook - Bravenet
I set up a Guestbook for my space using Bravenet - I fine-tuned the colours, fonts, etc., made it look real nice. If you embed it as a website in a book object, maybe put a quill and inkwell next to it, you're good to go!
Foundry Virtual Tabletop
While the witch dice integration is nice for dice rolling, an integration with Foundry VTT would allow 130+ tabletop RPGs to be played easily using Gather. unlike other Virtual table tops, Foundry VTT is all in-browser and could be a seriously cool integration!
This is available for all Miro boards, but you need to specifically copy the embeddable link for the board. Just follow the instructions in this link! https://help.miro.com/hc/en-us/articles/360016335640-Embedding-Editable-Boards-into-Websites
Having an API / integration with Slack so that members can be notified when users join / leave the server as well as synchronizing status messages and availability would be awesome! The ability to also offload screensharing to Slack (I've found the built in sharing to be too low quality for code review) would be a huge plus.