Image::Magick looks quite useful. I'll have to give that a try. By the way, after a cursory glance through the documentation, I didn't see how I could return the image directly to the caller, rather then saving it. Do you know how to do that?
Gracias

You'll want to print it to standard output. Per the docs, this would be:

$image->Write("gif:-");

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'

The code is extremely rough at this stage, and is an example of what not to put into production. There is much polishing to do.

#!/usr/bin/perl -w

use GD::Graph::bars;
use GD::Graph::Map;
use CGI qw/:standard/;
use Date::Calc qw/Delta_Days Date_to_Text Add_Delta_Days/;

my @data = ( 
    ["node1"],
);

my @dates = ("11-3-2002","12-4-2002", "15-5-2002","31-12-2002");
my $startdate = $dates[0];

for (my $i=0;$i<$#dates;$i+=1){
    my @basedate = split(/-/, $dates[$i]  );
    my @nextdate = split(/-/, $dates[$i+1]);
    my $dd = Delta_Days($basedate[2],$basedate[1],$basedate[0],
                        $nextdate[2],$nextdate[1],$nextdate[0]);
    push @data, [$dd];
}
my $my_graph = new GD::Graph::bars(200,500);

$my_graph->set( 
    x_label         => 'Node',
    y_label         => 'Date',
    title           => "Technology",
    y_max_value     => 365,
    y_tick_number   => 10,
    y_label_skip    => 2,
    y_number_format => \&y_format, 
    cumulate        => 1,
    borderclrs      => 'black',
    bar_spacing     => 4,
    bar_width       => 30,
    values_vertical => 1,
    accntclr        => 'lgreen',
    transparent     => 0,
);

sub y_format {
    my $val = shift;
    my @ysd = split(/-/, $startdate); 
    my @delta = Add_Delta_Days($ysd[2],$ysd[1],$ysd[0], int($val) );
    return substr(Date_to_Text(@delta), 4);
}

$my_graph->set_legend( qw(COM21 euroDOCSIS DOCSIS));
my $format= $my_graph->export_format;

if (length (my $info = path_info())) {
    print header("image/$format"), $my_graph->plot(\@data)->$format();
    my $map = new GD::Graph::Map($my_graph, info => '%l:  x=%x   y=%y'
+);
}


print header;
my $session = "graph";
my $map = new GD::Graph::Map($my_graph, info => '%l:  x=%x   y=%y');
print "hey this is way cool dude";
print  $map->imagemap(url()."/$session.png", \@data, noImgMarkup=>1);
[download]

The generated image is a one stacked bar, with dates on the y.

Merlyn has a column that sends a dynamically created image to the browser, from which I've learnt, and adapted.