How about:

%bighash = (%hash1,%hash2,%hash3);
[download]

Note that any duplicate keys will collide, and the value will be that of the the right most hash value... i.e. $hash3{dupe} will take precedence over $hash2{dupe} will take precedence over $hash1{dupe}.

Here is an example:

#!/usr/bin/perl -wT
use strict;

my %hash1 = (2 => 'cars',
             1 => 'motorcycle',
             4 => 'balloons',
             9 => 'came from hash1');

my %hash2 = (5 => 'airplanes',
             3 => 'helicopters',
             6 => 'skateboards',
             9 => 'came from hash2');

my %bighash = (%hash1 , %hash2);  # combine the two hashes

print "Hash1\n";
print "\t$_ => $hash1{$_}\n" for (sort {$a<=>$b} keys %hash1);

print "Hash2\n";
print "\t$_ => $hash2{$_}\n" for (sort {$a<=>$b} keys %hash2);

print "BigHash\n";
print "\t$_ => $bighash{$_}\n" for (sort {$a<=>$b} keys %bighash);


=OUTPUT
Hash1
        1 => motorcycle
        2 => cars
        4 => balloons
        9 => came from hash1
Hash2
        3 => helicopters
        5 => airplanes
        6 => skateboards
        9 => came from hash2
BigHash
        1 => motorcycle
        2 => cars
        3 => helicopters
        4 => balloons
        5 => airplanes
        6 => skateboards
        9 => came from hash2
[download]

-Blake