Hey PG folks.  I've attached two samples of code for creating the HMAC_MD5 pg_ts_hash in languages that you didn't already have listed in your documentation and developer's forum.  You are welcome to publish these examples.

For PERL:

#!/usr/bin/perl

use Digest::HMAC_MD5 qw(hmac_md5_hex);

# generate hex hash of message with secret key

my $digest = hmac_md5_hex("MESSAGE_TEXT","SECRET_KEY");

print $digest;

For Javascript:

<script type="text/javascript" src="http://crypto-js.googlecode.com/files/2.2.0-crypto-md5.js"></script>

<script type="text/javascript" src="http://crypto-js.googlecode.com/files/2.2.0-hmac-min.js"></script>

<script type="text/javascript">

     // Generate hex hash of message with secret key

     var hmac = Crypto.HMAC(Crypto.MD5, "MESSAGE", "SECRET_KEY");

</script>

[Contributor's notes]   I would not recommend the Javascript example as the Secret Key would be viewable by anyone who viewed the source of the HTML document, but it certainly works and for something like an intranet, or internal use only, it would be fine.