I use something like this. I was considering writing some small CPAN module and making this better...not sure how usable an entire module would be though.

sub round_it {
  my $num = shift;
  my $gb = (1024 * 1024 * 1024);
  my $mb = (1024 * 1024);
  my $kb = 1024;

   ($num > $gb) ? return sprintf("%dGB", $num/$gb) :
   ($num > $mb) ? return sprintf("%dMB", $num/$mb) :
   ($num > $kb) ? return sprintf("%dKB", $num/$kb) :
   return $num . 'B';
}
[download]

Anybody have any comments or suggestions?

Update: I think I stole some (or all?) of this code from merlyn sometime back...don't really remember.

perl -e 'print reverse qw/o b n a e s/;'