Did you base your code off of PHPDig? If so it would be a variant of PHPDig. PHPDig works well though some things could be better done and some fixes needed, I've thought about getting into the code and updating, not sure if I really have the time. Using the software for two client sites. So you going to put your version out to the public as open source or commerical? Just stumbled across Interactive Tools Website Search Engine,
http://www.interactivetools.com/prod.../features.html, for $49.00, may look into that as another possiblity.