Building a Progress Bar that Doesn't Progress

In many situations, accurately estimating the length of a certain process (copying a large file, loading data from a server, retrieving files from the Internet) would be both difficult and inefficient. What you end up with is a process that is going to take long enough to make the user wait, yet you have no easy way to indicate the percentage of the task that has completed. A regular progress bar would be rather meaningless, so you need some form of "Working…" indicator.