diff --git a/TimeSeries.pm b/TimeSeries.pm
index e673b0c..fd8fcdf 100644
--- a/TimeSeries.pm
+++ b/TimeSeries.pm
@@ -27,7 +27,7 @@ use Data::Dumper;
 use HTTP::Date qw(parse_date);
 use Time::Local qw(timegm_nocheck);
 
-$VERSION = do { my @r=(q$Revision: 1.11 $=~/\d+/g);sprintf "%d."."%02d"x$#r,@r};
+$VERSION = do { my @r=(q$Revision: 1.12 $=~/\d+/g);sprintf "%d."."%02d"x$#r,@r};
 
 =head2 new(%opts)
 
@@ -192,6 +192,21 @@ sub log_y {
     return $oldlog_y;
 }
 
+=head2 stacked([$stacked])
+
+If $stacked is non-zero, the timeseries are stacked.
+
+The return value is the old value of this setting.
+
+=cut
+
+sub stacked {
+    my ($self, $stacked) = @_;
+    my $oldstacked = $self->{stacked};
+    $self->{stacked} = $stacked if (defined($stacked));
+    return $oldstacked;
+}
+
 =head2 output_format([$output_format])
 
 Sets a new output format if $output_format is given. In any case the old
@@ -301,14 +316,22 @@ sub plot {
     my ($self) = @_;
     #print Dumper($self);
 
-    my ($datafh, $datafn) = tempfile();
+    my ($datafh, $datafn) = tempfile("tsplotXXXXXXXX", UNLINK => 0);
     for my $i (@{$self->{data}}) {
 	my $time = $i->[0];
 	my $data = $i->[1];
 
 	print $datafh $time;
-	for my $j (@$data) {
-	    print $datafh "\t", $j + 0;
+	if ($self->{stacked}) {
+	    my $v = 0;
+	    for my $j (@$data) {
+		$v += ($j || 0);
+		print $datafh "\t", $v;
+	    }
+	} else {
+	    for my $j (@$data) {
+		print $datafh "\t", ($j || 0) + 0;
+	    }
 	}
 	print $datafh "\n";
     }
diff --git a/top_n b/top_n
new file mode 100755
index 0000000..1630e63
--- /dev/null
+++ b/top_n
@@ -0,0 +1,42 @@
+#!/usr/bin/perl -w 
+use strict;
+
+my $n = shift;
+my $f = shift;
+my $v = shift;
+
+my @data;
+my %s;
+while (<>) {
+    chomp;
+    my @a = split(/\t/);
+    push @data, [@a];
+    $s{$a[$f]} += $a[$v];
+}
+
+my @top_n = (sort { $s{$b} <=> $s{$a} } keys %s )[ 0 .. $n - 1 ];
+my %top_n = map { $_ => 1 } @top_n;
+
+my %index;
+
+for my $i (0 .. $#data) {
+    unless ($top_n{$data[$i][$f]}) {
+	my $val = $data[$i][$v];
+	$data[$i][$v] = 0; 
+	$data[$i][$f] = 'UNKNOWN';
+	my $k = join("\t", @{$data[$i]});
+	if (defined($index{$k})) {
+	    $data[$index{$k}][$v] += $val;
+	    $data[$i][$v] = undef; 
+	} else {
+	    $data[$i][$v] = $val; 
+	    $index{$k} = $i;
+	}
+    }
+}
+
+for (@data) {
+    if (defined($_->[$v])) {
+	print join("\t", @$_), "\n";
+    }
+}
diff --git a/tsplotv b/tsplotv
new file mode 100755
index 0000000..80fa693
--- /dev/null
+++ b/tsplotv
@@ -0,0 +1,41 @@
+#!/usr/bin/perl -w 
+
+=head1 NAME
+
+tsplotv - plot time series given in vertical format
+
+=head1 DESCRIPTION
+
+This program expects time series data in vertical format, I.e.,
+each line contains a tripel <time, series, value>. 
+
+=cut
+
+use strict;
+use TimeSeries;
+
+binmode STDOUT, ':raw';
+
+my %series;
+my $ns;
+my %data;
+
+my $ts = TimeSeries->new();
+while (<>) {
+    chomp;
+    my ($timestamp, $series, $value) = split(/\t/);
+    $series{$series} = ++$ns unless ($series{$series});
+    $data{$timestamp}{$series} = $value;
+}
+my @series = sort { $series{$a} <=> $series{$b} } keys %series;
+$ts->legend(@series);
+$ts->legend_position("below");
+$ts->stacked(1);
+for my $timestamp (sort keys %data) {
+    my %d = %{$data{$timestamp}};
+    my @values = @d{@series};
+    $ts->add_timestring($timestamp, @values);
+}
+
+my $g = $ts->plot();
+print $g