You could List::Util::shuffle or fisher-yates the directory and then take a slice of the resulting array.

!/usr/bin/perl -wd

use IO::Dir;

tie %dir, IO::Dir, ".";
@files = grep { -f } keys %dir;
fisher_yates_shuffle( \@files );

print $files[$_],"\n" for 0 .. 5;

# right from the faq
sub fisher_yates_shuffle {
    my $deck = shift;  # $deck is a reference to an array
    my $i = @$deck;
    while ($i--) {
        my $j = int rand ($i+1);
        @$deck[$i,$j] = @$deck[$j,$i];
    }
}
[download]

or

!/usr/bin/perl -wd

use IO::Dir;
use List::Util 'shuffle';

tie %dir, IO::Dir, ".";
@files = grep { -f } keys %dir;

@shuff = shuffle(@files);
print $shuff[$_],"\n" for 0 .. 5;
[download]

-derby