sleep with a progressbar.
nap is a special implementation of sleep. The main difference is the presence of a progressbar: nap prints out a progressbar and shows how much time has already elapsed. It is useful for impromptu “scheduling”, so you know when will the process/wait finish.
nap takes the best features from both the GNU and BSD variants of sleep: it values BSD-style simplicity, but also supports GNU-style input with units (s|m|h|d).
See also: think — Terminal Think Music