I like to use Date::Manip, but it is rather large.
http://search.cpan.org/~sbeck/Date-M...Date/Manip.pod
You can do a TON of stuff with this module. Run the pod to text to get the full help text with formats, date calculations, etc.
use Date::Manip;
$ENV{TZ}="EST";
use strict;
use warnings;
my $ptoday=ParseDate("today");
my $ftoday=UnixDate($ptoday,"%m/%d/%Y");
print "$ftoday\n";
my $month=UnixDate($ptoday,"%m");
my $day=UnixDate($ptoday,"%d");
my $year=UnixDate($ptoday,"%Y");
my $dayofyear=Date_DayOfYear($month,$day,$year);
print "$dayofyear\n";