Interesting, I think 'split' when I see something separated by slashes. Off the top of my head, the below code will do what you are looking for:

my @dirs = qw (
/usr/local/bin/
/var/tmp/somefile
/
/home/foo/bar
);

foreach ( @dirs ) {
    my @dir;
    my $lastdir;

    if ( /^\/$/ ) {
        $lastdir = "/";
        print "$lastdir\n";
        next;
    }

    if ( /\/$/ ) {
        chop;
    }

    @dir = split('/');
    $lastdir = pop(@dir);
    print "$lastdir\n";
}
[download]

Will print:

bin
somefile
/
bar

Sorry if this is hacky code. I'm a Monks newb and have made my career by pounding out this type of randomness.