A very simple timer with start/stop button for each task would mean the world for me. Available to start/stop on mobile app. For administrative purposes it would be rally useful to have that option right next to each task, and i could see how long someone worked on it. Time is not only a costing item but project management item. I know asana has integration with Harvest etc. But they are all annoying for me and require you to pay extra.
Given the deep integration of Harvest, I guess that means Asana has no plan for such a feature before for some time. Your only chance is to find a developer and build the same service for free
This is a great, must have future, I was just about to creat the same topic. Another one that you might find it useful too is estimated time for a task.
A start time would be useful for connecting to an outside calendar (ie. Google) then one can schedule the tasks in their week without having an extra step.
I also agree with others in how this would work well with a meeting.
I would suggest a simple digital timer like TMetric - it will provide with the most precise calculations