On the site http://clustrmaps.com/ you can get a nice gadget that can be implemented on your site. It is a worldmap that shws you where your visitors come from. In the beginning it will be empty, but after a while (and with foreign visitors) the image will build up. I have placed it on top of the sidebar on this blog for this moment. You can now see immediately what countries the visitors come from.
Other statistical programms have this option too. But Clustrmap shows the image straight away on the site for all to see.