Task Flow chart capability for project task viewing (ex. Visio, other)

In addition to Gantt charting capability, there is interest in flow charting capability to show how tasks are linked and decipher what happens when. This would increase interest in the tool through ease of use and ease of interpretation of project status. This is similar to Gantt charting, but would incorporate the task name within the flow chart, rather than the way that Gantt charts are laid out (tracing the task name to the line in the Gantt chart). I have seen other systems that contain a flow chart in the background, but aim of this would be to select flow chart in place of Gantt or list style. This may be a very useful tool to visualize projects in addition to task status. As part of this, greying out completed tasks would help to visualize the current task status.