Geoplugin is a webservice which allows you to find Location based upon the IP of the client. It shows City, region, country, latitude , longitude etc of the IP address. Its very easy to integrate in your running website, using following code:

And it will return you the results. It supports various formats like PHP, JSON, ASP, XML etc.
You can check LIVE DEMO HERE

Geo plugins also provides currency converter plugin as well, and it is also very easy to integrate, a sample code is given below:

–find location from ip address in php