As a product owner I'd like to be able to have a constant visual reminder (like the mentions and activity tags) for personal todo's in a ticket, so that I don't forget to finish that task. Having to keep track of multiple collections and boards makes it hard to have a complete overview of certain tasks and tickets that need extra attention. The possibility of adding personal todo's (by me or my team mates) in a ticket and adding them into a list will make my life a whole lot easier. Now I can work my way through those items and never forget to finish a task.
Picture this: A backlog item I worked on needs some extra refinement. My team mate mentions me in the ticket and gets a mention tag in the backlog. I open that ticket and the tag disappears. Now I need to leave my computer to go into a meeting. There's no visual reminder anymore that I needed to do something for that ticket. The card disappears between all the rest of the rest of the backlog items and I forget to do the task that was appointed to me. And to top it all off, my team mate is pissed off because I haven't done my work.
Solution: personal todo's! Me or my team members should be able to add a personal todo's in a ticket, which I can set to done when finished. All my personal todo's should be added in a todo list (next to activities and mentions), which can contain todo's for multiple tickets. Tickets that have a personal todo should have a constant visual reminder for me in any view which should disappear when the personal todo is set to done. Result: a happy life for everyone!