Just pick a random position in the file and seek() backwards until you find the line separator or the beginning of the file e.g

open(my $f, $your_file) or die("ack: $!");
seek($f, int rand(-s $f), 0);
{
  local $/ = \1;
  ## anyone care to optimise this?
  seek($f, -2, 1) until ($c = <$f>) eq "\n" or tell($f) == 0;
}
print scalar <$f>;
[download]

That should print out a random line in a file without having to do a slurp.
HTH

_________
broquaint