Here's some 'work in progress' - ie, it'll never be finished.., but as it finally works, I thought it was time to let it loose in the Monastry for taming... It produces surreal limericks of the 'Edward Lear' type (ie, not very funny and having a last line based on the first), but they rhyme, scan, and sometimes almost make sense.
I wanted to use Lingua::EN::Rhyme, but it needs a MYSQL db setting up, so I plumped for parsing rhymezone.com instead. I was also, up to last night, picking a random location from WWW::Gazetteer::HeavensAbove, but suddenly the server stopped...hope it wasn't me :) So for now, supply a placename as an argument.
Again, for the random words, I wanted to use Lingua::EN::Dict, but it's seriously broke :( so instead it picks random words from /usr/share/dict and looks them up using Net::Dict.
It can be a little slow (lots of lookups), hence the 'I'm still working' print statements.
All suggestions welcome :)

#!usr/bin/perl

# SurreaLearruS 

use strict;                                            # as if...
use Net::Dict; # lookups for word type
# use WWW::Gazetteer::HeavensAbove;    #when it works again, random pl
+aces..
use Lingua::EN::Syllable;
use LWP::Simple;
use Algorithm::Numerical::Shuffle qw /shuffle/;        # Ta Abigail :)

my $place = @ARGV[0] or die "Usage - limerick placename\n";
my $dict = Net::Dict->new('dict.org');
my $prhyme = rhyme($place,'n') or die "No rhyme for $place!\n";
print "found rhyme for $place...\n";
my $place_syll = syllable($place);    
# set up word array, 
my @words;                # thanks to BrowserUK :)
open FILE, '<', '/usr/share/dict/words' or die $!; # I liked Tie::File
+ solution too, 
while(<FILE>) {push @words, tell FILE;}    # but needs permissions to 
+rw dict..
print "loaded words\n";
my %people = (                #people, syllables and s/he
    'lady'=>[2,'s'],
    'woman'=>[2,'s'],
    'man'=>[1],
    'boy'=>[1],
    'girl'=>[1,'s']
);                                                    # etc..
my @people = keys %people;
my $person = $people[int(rand(@people))];
my $psyllables = $people{$person}[0];
my $gender = $people{$person}[1];
my $qualifier = int(rand(2));
if ($qualifier) {
    $person = ((int(rand(2))) ?'old ':'young ').$person;
    $psyllables++;
}
print "got person...\n";
my $conj = ('by','with','in')[int(rand(3))];
my $noun1 = rand_word('n');
print "picked 1st noun...\n";
my ($noun2,$n2rhyme);
while (!$n2rhyme) {
    $noun2 = rand_word('n');
    $n2rhyme = rhyme($noun2,'n');
}
print "picked 2nd noun & rhyme...\n";
my $once = 'once' if ($psyllables + $place_syll) < 4;
print "There $once was ",indef($person)," $person from $place,\n",
    "who ",past(rand_word('v'))," ",indef($noun1)," $noun1 $conj ",ind
+ef($prhyme)," $prhyme,\n",
    $gender,"he ",past(rand_word('v'))," ",indef($noun2)," $noun2,\n",
    "and ",past(rand_word('v'))," ",indef($n2rhyme)," $n2rhyme,\n",
    "that ",rand_word('adj')," $person from $place.\n";
close FILE;
exit;

sub rhyme {
    my ($word, $type) = @_;
    my $page = LWP::Simple::get("http://www.rhymezone.com/r/rhyme.cgi?
+Word=$word&typeofrhyme=perfect&org1=syl&org2=l");
    my @rhymes;
    push @rhymes, $1 while ($page =~ /HREF="d\?u=(\w+?)"/sg);
    @rhymes = shuffle (@rhymes);
    foreach (@rhymes) {
        return $_ if ($_ ne $word && word_type($_) eq $type);
    }
    return 0;
}

sub rand_word {
    my $type = shift();
    my ($word,$t);
    my $start = rand(@words);
    while ($t ne $type) {
        $start = 0 if ($start++ > $#words);
        $word = do{ seek FILE, $words[$start], 0; <FILE>;}; 
        chomp $word;
        next if ($word eq ucfirst($word));#skip proper nouns
        $t = word_type($word);
    }
    $word;
}

#parse Wordnet Definition for 'n 1:' etc...
#will be improved to take all meanings into account - for now just ret
+urn first one.
sub word_type {
    my $word = shift();
    my $h = $dict->define($word,'wn');
    $h->[0][1] =~ /\b(\w+)\s+1?:/s;
    return $1;
}

sub get_places {    #awww - it was so sweet too...:)
    my ($pattern,$country) = @_;
    my $atlas = WWW::Gazetteer::HeavensAbove->new;
    my @az = $atlas->find($pattern,$country);
    return @az;
}

sub indef {return ((shift =~ /^[aeoiu]/i) ? 'an' : 'a');} #dodgy, but 
+works for most cases :)

sub past {my $v = shift(); return ($v =~/^(.*)y/) ?$1.'ied' : $v .(($v
+ =~/e$/) ? "d":"ed");} # even dodgier!
[download]

My favourite so far......

 There once was a lady from york,
 who amassed an unpleasantness with a stork,
 she reestablished a hull,
 and imperiled a cull,
 that barometric lady from york.
[download]

Enjoy!
Update - fixed the gender and 'once' bugs.
Update2 - improved 'past'