Fluster is a clustering algorithm for the Google Maps API v3. It manages all your markers on the map and summarizes them to "clustered markers" if there is not enough space around them. Acts like MarkerClusterer for v2.
I really like this plugin. It´s clustering fast and it´s easy to use. The lack of documentation is the only negative thing I can think of right now. We are using it on www.genteycasas.com/en-us/115/inmuebles-en-mapa/bogota if you want to check it out. Thanks!