I like this idea.

Maybe the simplest implementation would be to add an "I'm Interested" button to interest checks. You get added to the public list of interested users for that interest check. And maybe it can lead to players contacting each other like: "Hey, I saw you were interested in X. Want to start one with me?"

For the interest check creator, I can then create a message box below the list of interested players that lets them send a message to the entire list. It can be used to announce the roleplay created from the interest check and perhaps any future roleplays spawned from it in the future. Though I'm not sure how I want these sorts of messages to piggy-back on top of the current system. For instance I don't think the message box should create a big group convo. Maybe I can introduce a new notification type that encloses the attached message.

Finally, players can see a list of all interest checks they're interested in and remove themselves.

Maybe there's a better idea, but the above is at least doable and not a massive undertaking.