I've used the practice you outline to process human-list-reports into nice, machine-treatable reports to great success, except without the slurping part:

package Parser::ReportFoo;
use strict;

sub new {
    ...
    $self->columns = [qw(date customer amount)];
};

my @handlers = [
    # Line containing uninteresting information
    [qr/^Line containing uninteresting information/ => \&discard],
    [qr/^------------/ => \&discard],
    [qr/^(\d\d-[A-Z]{3}-\d\d)     (..........) (\d+\.\d+)/ => \&captur
+e_transaction],
    [qr/^\s*$/ => \&flush ],
    [qr/^         )     (..........)\s+$/ => \&capture_name2],
];

sub discard {};

sub flush {
    my ($self) = @_;
    my @row = map { $self->$_ } (@{ $self->columns });
    print join "\t", @row;
};

sub capture_transaction {
    my ($self,$date,$customer,$amount) = @_;
    $self->date($date);
    $self->customer($customer);
    $self->amount($amount);
};

sub capture_name2 {
    my ($self,$customer) = @_;
    $self->customer($self->customer . " " . $customer);
    $self->flush();
};

sub parse {
    my ($self,$file) = @_;
    my $fh = open "<", $file or die "$file: $!";
    while (defined my $line = <$fh>) {
        # First, check which regex 
        my $handled;
        for (@handlers) {
            my ($re,$code) = @$_;
            if (my @match = ($line =~ /$re/)) {
                $code->($self, @match);
                $handled = 1;
                last;
            };
        };
        warn "Unhandled line >>$line<<";
    };
};
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The separation of flush() and capture_foo is because I have sometimes reports where one logical row spans several lines or where the transaction date is noted at the top of the "page", so some information has to persist before a whole line can be printed to the results.

I use tab separated files with a file extension of .xls which is the most Excel friendly thing you can get without involving Win32::OLE or SpreadSheet::WriteExcel.

Update: monarch spotted a typo/error in sub parse, I was using @_ where it should have been @$_.