Would love for this feature to be implemented, we need it moreso now that we have got more people using Discourse for project management. We just discuss things and actionable things pop up regularlay, and we “mark” them by adding a checkbox, so that nothing is forgotten and missed later. After that, it would be super convenient if there would be a checkboxes summary list that shows all checkboxes–either from the current topic or from a category–and optionally unchecked only, or unchecked first, then checked.