Shell Scripting: A Low-precision Visual Timer

For many years, I've wanted a simple command-line timer program to use in conjunction with short human tasks — the sort of thing my wristwatch timer works for, but I'm not always wearing that watch. I want something that provides some indication of elapsed time or time remaining. Amazingly, the commercial Unixes I'm familiar with do not provide such a utility; nor does one seem to be readily available with the standard X Window tools.