Perltidy is a Perl script which indents and reformats Perl scripts to make them easier to read by trying to follow the rules of the perlstyle. If you write Perl scripts, or spend much time reading them, you will probably find it useful. It is available at http://perltidy.sourceforge.net
Of course, if you simply follow the guidelines in perlstyle, you shouldn't need to reformat. The habit of formatting your code as you write it will help prevent bugs. Your editor can and should help you with this. The perl-mode or newer cperl-mode for emacs can provide remarkable amounts of help with most (but not all) code, and even less programmable editors can provide significant assistance. Tom Christiansen and many other VI users swear by the following settings in vi and its clones:
set ai sw=4
map! ^O {^M}^[O^TPut that in your .exrc file (replacing the caret characters
with control characters) and away you go. In insert mode, ^T is
for indenting, ^D is for undenting, and ^O is for blockdenting--
as it were. A more complete example, with comments, can be found at
http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz
The a2ps http://www-inf.enst.fr/%7Edemaille/a2ps/black+white.ps does lots of things related to generating nicely printed output of documents, as does enscript at http://people.ssh.fi/mtr/genscript/ .