HTML:
<input id="a_input_id" type="text">
<a href="#" class="special_field_link">http://www.ParHost.net<a>
JS:
$(function(){
$('.special_field_link').live('click', function() {
$("#a_input_id").val($(this).html());
});
});
Also, you can use .text() instead of .html() as listed in this answer: Fill in Input Field by Clicking Link with JQuery
Running Sample: http://fiddle.jshell.net/s8nUh/