http://httpd.apache.org/docs/1.3/mod/mod_rewrite.html

In your .htaccess file, you can specify re-write rules that will convert the url to whatever you want it to look like. With this, you can "encode" all the variables info into what looks like a normal url, then "decode" you own code if it's resubmitted.

Another useful page on this specifically:

http://www.devshed.com/c/a/Apache/Search-Engine-Friendly-URLs-with-mod-rewrite/

If you want to hide the specific contents of the parameters, then just don't send them. Create an opaque token (say a random sequence of digits, or run the serialized contents of the real parameters through Digest::SHA1) and send the token back as the sole parameter. Then map that token back to the information on the server side and process it as needed.

1. Parse the querystring and create hidden field for each name/value p
+air by 
   document.write("<input type=hidden name="+ name + " value ="+ value
+>");

2. Make the form method to POST
    document.form.method="POST";

3. Specify the form action 
   document.form.action="http://127.0.0.1/cgi-bin/test.cgi";

4. Do the form submit
     document.form.submit();
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<script type='text/javascript'>
  function submitForm ( formName ) {
    document.getElementById( formName ).submit();
    return true;
  }
</script>
<form action="http://127.0.0.1/cgi-bin/test.cgi" method='POST' id='tes
+tForm'>
<input type=hidden name='name' value='tom'>
<input type=hidden name='value' value='12'>
<input type=hidden name='id' value='52345'>
<input type=submit value='Test Link as Button'>
<a href="http://127.0.0.1/cgi-bin/test.cgi" 
 onClick = "submitForm('testForm');"
 onMouseOver = "window.status = 'http://127.0.0.1/cgi-bin/test.cgi'; r
+eturn true;"
 onMouseOut = "window.status = ''; return true;"
>Test Link</a>
</form>
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<A HREF="http://127.0.0.1/cgi-bin/test.cgi/tom/12/52345">Test Link</A>
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my $extra_path_info = $ENV{'PATH_INFO'};
# or
use CGI;
my $query = new CGI();
my $extra_path_info = $query->path_info();

print $extra_path_info;
# prints '/tom/12/52345'
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<script type='text/javascript'>
  function submit_cookies ( formId ) {
    var thisForm = document.getElementById( formId );
    if( ! thisForm ) return true;

    var formLocation = thisForm.action;

    // Run through all the form variables and convert
    // them all to cookies
    for( var i = 0; i < thisForm.elements.length; i++ ) {
      var elementName  = thisForm.elements[i].name;
      var elementValue = thisForm.elements[i].value;
      document.cookie = elementName + '=' + elementValue + ';';
    }
    window.location = formLocation;
    return true;

  }
</script>
<form action="https://vmacs.vmth.ucdavis.edu/echo" method=POST id='tes
+tForm'>
  <input type=hidden name='name' value='tom'>
  <input type=hidden name='value' value='12'>
  <input type=hidden name='id' value='52345'>
  <a href="#" onClick="submit_cookies('testForm');">Test Link</a>
</form>
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• Use frames to hide the destination URL
• Open the other document in an iframe
• Use AJAX to have javascript do the request for you (works with GET or POST), then rewrite the current page and location
• Once the destination page receives the parameters, send them all back as cookies (or store them and send back a token, or something) and then quickly update the URL to remove the parameters

Thank you very much for your posting these examples. It really helped me.

If the parameters are not passed in the url, how are they going to get to the script? They need to be somewhere, and if you can't POST to the form (because you're using a link) then you're pretty much out of luck.

Thank you all who have responded to my question.