retrieve zipcode or location of client

Best you can do is a use a GEOIP data base to map IP addresses from the header. Not particularly accurate though. My IP block maps to my ISP's business office - 2500 miles away. Proxy's tend to mask IP addressess as do some firewalls and browser extensions.

I use MaxMinds GeoIP Country on this site to get the country the user is from based on their IP address.

I find it very accurate at getting the correct countries based on the users IP, I've also written a function that can workout the continent the user is from based on their country code. PM me your email address if you would like a copy of this country code to continent code function.

I use it on this site to block certain counties that are hotspots for software pirating, hacking, and fraudulent transactions.

I also use the it with the continent function I have written to display pricing in the purchasing section in a currency more relevant to the user, eg. If you are in Europe it displays in Euros by default.

You can get GeoIP from www.maxmind.com

Edited by -boRg- - 18 September 2006 at 10:55am