I am building one that as a focus on the Tasks for Today, and while I am building it I am actively using it to plan my work day.
The plan is to integrate it with Gitlab, Github, Jira, etc., so that I can have a unified view of everything I want to get done today. It will have a tab for Professional and Personal life. It will support priorities, notes, comments, topics, groups, backlog, permalinks, realtime updates, etc.
If you are wondering what the copy button is for:
I can now select what I want to copy to the clipboard in html format, thus when I past it in my Gmails it will have the same look, but if I paste it in my editor I get only the text.