Offer based on GEO Location, script

Im looking for a script that loads an offer based on GEO IP / location.

When a user visits my site if they click on my offer and they are from Australia it load up the offer pertaining to offers available in Australia only. Likewise, if the user is from the US then it takes the user to the offer for US based customer only.

Is there such a script? If there is and i have missed it i apologize. Please direct me to the correct url.

Thanks