Assigning and Tracking Sprint Tasks with a one stop UI

Having worked for nearly 18 months using the Scrum development process I have to say that I really like the idea of Sprints. However I find that tracking the amount of effort actually expended on tasks is hard. Without those numbers it is extremely difficult to measure and improve the accuracy of task estimates. As befits my kind (Engineer), I have thought of many technology solutions to this problem.

The latest amongst these is a Sprint Task Tracker which lets you assign work to people by clicking on their picture amongst a gallery of portraits lined up beside each task. As soon as a person is assigned to a task they are seen to be expending effort on it. If they are assigned to two or more tasks, their effort is calculated as being split evenly between them. A pair of people working full time on a task means twice as much effort being expended on it.

Sprint Task Tracker would keep track of individual effort expended per task. Information such as total effort expended per team member on sprint tasks as well as total combined effort on a given task could be gleaned from this. Clicking on an active team member takes them off a task and they stop building effort towards it. The remaining time for a task could be calculated as the estimated time minus the total combined effort. When remaining time reaches zero an alert icon would appear by the task suggesting that it is time to re-estimate or mark the task complete.

A separate Sprint Burndown interface could use the total combined remaining time to plot a burdown chart showing the progress of the sprint.

Am I crazy? Is this yet another stupid Scrum app doomed to failure? Tell me by sharing your comments...