Live URL hash updating as you drag a Google Map around. That way the URL is always the permalink for your current viewport.

zoom hashes in Google Maps

function makeLink() {
    location.hash = "#/"+map.getCenter().lat().toFixed(3)+"/"+map.getCenter().lng().toFixed(3)+"/"+map.getZoom();
}

function initialize() {

    var query = location.search.substring(1);

    var lat = 0.5;
    var lng = 0.5;
    var zoom = config.defaultZoom;

    // Jeff's hash rewriting:
    var hash = window.location.hash
    var params = hash.split("/")
    if (params.length > 1) {
    lat = parseFloat(params[1])
    lng = parseFloat(params[2])
    zoom = parseInt(params[3])
    }

    var mapOptions = {
        zoom: zoom,
        center: new google.maps.LatLng(lat, lng),
        navigationControl: true,
        scaleControl: false,
        mapTypeControl: mapTyepControlToggle,
        mapTypeControlOptions: {
            mapTypeIds: mapTypeIds
        },
        mapTypeId: mapTypeIdDefault,
        streetViewControl: false,
        backgroundColor: config.bg_color,
    };
    map = new google.maps.Map(document.getElementById('mcmap'), mapOptions);

}