Smart progress bar ETA computation

Question

In many applications, we have some progress bar for a file download, for a compression task, for a search, etc. We all often use progress bars to let users know something is

Answer 1

I always wish these things would tell me a range. If it said, "This task will most likely be done in between 8 min and 30 minutes," then I have some idea of what kind of break to take. If it's bouncing all over the place, I'm tempted to watch it until it settles down, which is a big waste of time.