One of the greatest graphs I’ve seen at Microsoft is this one that a colleague of mine put together as Windows 95 was nearing completion. He took each email message from management that changed the Windows 95 RTM date (also known as the ship date) and plotted it on a chart. The x-axis is the date the statement was made and the y-axis is number of days remaining in the project, according to the email. The dotted line is a linear least-squares fit, and the green star is the actual ship date (July 14, 1995).
Source: Insightful graph: The ship date predictor – The Old New Thing – Site Home – MSDN Blogs