The "twirling baton" is another simple progress indicator that may be more suited to large jobs with indeterminate ends. Here's a simple implementation that I wrote years ago, long before even finding this site:

BEGIN {
  my @chars=('-','\\','|','/','-','\\','|','/');
  my $step=0;
  sub baton_start { $step=0 ; goto &baton_step }
  sub baton_step { print STDERR $chars[$step++],"\b";
                  $step=0 if $step >=8 }
  sub baton_end { print STDERR "\b "; }
}
[download]

I have used this in many one-off scripts and I generally just copy and paste it when needed, since it is so simple.