With GMaps.js you can use a marker clusterer to group large amount of markers:
map = new GMaps({ div: '#map', lat: -12.043333, lng: -77.028333, markerClusterer: function(map) { return new MarkerClusterer(map); } });
You can use MarkerClusterer or MarkerClustererPlus. If you want to use a custom marker clustering library, you have to define a addMarker
method.
Note: Read more about MarkerClusterer and MarkerClustererPlus here.