Here's a short script to find all apartment rentals on Craig's list for the San Francisco Bay area, given an address and the distance (in miles). Some notes:

• You can easily add real-estate listings, room-to-share, etc., by changing the base url in the code
• You can also use Craig's list for other metropolitan areas, again by changing the base url. I think this only works for US, since it uses google maps to find the latitude/longitude, google maps doesn't seem to have GIS data for other regions.
• The script takes two arguments: the address (quote it), and the distance in miles. You can easily change the unit by passing the appropriate string to Geo::Distantce.
• I'm outputting to stdout, you can certainly print to html files to make the links.
• Like other scraping code, this will need to be updated if either Craig's list or Google maps change their html.

#!/usr/bin/perl -w
use strict;
use WWW::Mechanize;
use Geo::Distance;
use URI::Escape;

unless (@ARGV==2){
    print "Usage: need to pass the address (in quotes), and the distan
+ce.\n";
    exit 0;
}

my $address = $ARGV[0];
my $dist = $ARGV[1];
my $num_pages = 10; # number of craiglist pages to process, be nice!

print "\nFinding apartment listings within $dist miles from $address\n
+";

my $agent = WWW::Mechanize->new();
my $google_reg = qr{<point lat="([-\d\.]+)" lng="([-\d\.]+)"/>};

# first, find long/lat for the address using google maps.
my $googlemap = "http://maps.google.com/?q=".uri_escape($address);
$agent->get($googlemap);
my ($my_lat,$my_long) = $agent->content() =~ /$google_reg/i;
print "You're at longitude=$my_long, latitude=$my_lat\n\n";

# now crawl craig's list for listings
my $geo = new Geo::Distance();
my $site = "http://www.craigslist.org";
my $url = "$site/apa/";
process_page($_) foreach $url, map{$url."index${_}00.html"}(1..$num_pa
+ges);
exit(0);

sub process_page{
    my $u = shift;
    my ($price,$title,$ul,$lat,$long);
    $agent->get($u);
    my @links = $agent->find_all_links(url_regex=> qr{/apa/(\d+)\.html
+}i);
    foreach my $link(@links){
        if($link->text() =~ /^\s*\$([\d,]+)\s+/i){
            $price = $1;
            $title = $link->text();
            $ul = $site.$link->url();
            $agent->get($ul);
            $agent->follow_link( text => "google map");
            ($lat,$long) = $agent->content() =~ /$google_reg/i;
            my $d = $geo->distance('mile',$my_long,$my_lat => $long, $
+lat);

            if($d <= $dist){
                print "price: \$$price\n";
                print "distance: $d miles\n";
                print "title: $title\n";
                print "url: $ul\n\n";
            }
        }
    }
}
[download]