Here is a 1 minute demo of the time travel debugging feature in Yazz, which is a rapid application development tool in progress at Yazz.com. I am not affiliated with the Yazz project, but thought it would be fun for the FoC group to see how some people are attacking that crucial problem of going in reverse. This demo shows a bubble sort, and tracks each line of the code as it executes, and shows the changing state of the data. The concept of having one little square's position vertically be based on the line number of the code doesn't scale well, but for small examples it is very cute.