Magento Language and Currency Switcher Extension by FMEExtensions is a top selling module for webstores looking to internationalize their site. This module allows you to serve the customers in different regions without requiring additional domains. You create different stores on your website for your needs and this module will automatically display the appropriate store to incoming visitors. This GEO IP module automatically picks up the location of customers and hence, it can select appropriate store. Customers can manually switch different stores as well.

Key Features:

a) Auto language and currency switcher
b) Auto location tracking
c) Customers can manually switch stores
d) IP exclusions supported
e) ACLs supported

and many more valuable features are included. Please check free demo, more description on the following link;

http://www.magentocommerce.com/magento-connect/geo-ip-language-currency-switcher.html