Having been asked, I posted a mySQL dump of latitude, longitude and zip codes for the US. I've also included a PHP zipcode computational piece of code, a DB manager, and the page itself.... all in GZIP format. Instructions are on the page.
P.S. I can't possibly help you if you're having problems! Unzip it all, put the dump into mySQL, edit the db.inc file (username/pwd/host/db_name), run the ziptest1.php script, and if it works GREAT! If it doesn't... you'll have a new opportunity to learn! I would never want to take that away from you :-) It works for me, so if it doesn't work for you, I probably can't fix it.
Paul Dacus
