Clustr maps allow you to see at a glance where your site's visitors are located. Even when the numbers are enormous it seems. Visitors don't need to click on anything - just viewing your page is enough.

One thumbnail map on your site reveals all and Clustr provide (free) the HTML that gives you a thumbnail map. When it loads, it increments a counter and shows the locations of all the visitors to your page, cumulatively (even for huge numbers). Clicking on it zooms in to a big world map, and (optionally) lets you zoom in to the continents. There you have it - your own big brother.