Create a Visualforce page to show all your customers addresses on Google Maps. Note there is a limit on the amount of Map pins that are set thus I created a timeout of a few seconds so Google does not show me pop-up an error message.
<apex:page controller="getCustomerAddress" sidebar="false" showChat="true">
<html>
<head>
<script type="text/javascript" src="https://maps.google.com/maps/api/js?sensor=false"></script>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type="text/javascript">
var arraddress= new Array();
var arrids= new Array();
var content=new Array();
var arrnames= new Array();
var i=0;
var map;
var geocoder;
function initialize()
{
var mapDiv = document.getElementById('map-canvas');
map = new google.maps.Map(mapDiv,
{
zoom: 4,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
);
google.maps.event.addListenerOnce(map, 'idle', addMarkers);
}
function addMarkers()
{
for (var i = 0; i < arraddress.length; i++)
{
content[i] = arrnames[i]+' '+arraddress[i];
geocodeAddress(arraddress[i],arrids[i],content[i]);
}
}
function geocodeAddress(addds,id,content)
{
geocoder = new google.maps.Geocoder();
geocoder.geocode( { 'address': addds}, function(results, status)
{
if (status == google.maps.GeocoderStatus.OK)
{
map.setCenter(results[0].geometry.location);
var marker = new google.maps.Marker({map: map,position: results[0].geometry.location});
var infowindow = new google.maps.InfoWindow({content: content});
google.maps.event.addListener(marker, 'mouseover', function() { infowindow.open(map,this);});
google.maps.event.addListener(marker, 'mouseout', function() {infowindow.close();});
google.maps.event.addListener(marker, 'click', function() { window.open('/'+id);});
}
else if (status == google.maps.GeocoderStatus.OVER_QUERY_LIMIT)
{
setTimeout(function() {geocodeAddress(addds, id, content);}, 200);
}
else
{
alert("Geocode was not successful for the following reason: " + status);
}
});
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
</head>
<body style="font-family: Arial; border: 0 none;">
<div id="map-canvas" style="width: 1500; height: 750px"></div>
<apex:repeat value="{!Address}" var="a">
<script>
arraddress[i]= '{!a.BillingStreet}, {!a.BillingCity}, {!a.BillingPostalCode}, {!a.BillingCountry}';
arrids[i]='{!a.id}';
arrnames[i]='{!a.name}';
i++;
</script>
</apex:repeat>
</body>
</html>
</apex:page>
Thys Michels Blog 
Where is “getCustomerAddress” class ?
Do you have Test Class for this?