Integrating Google Maps with custom marker and hover?

I want the exact output of this site. I want to edit the marker and hover options in the Google map, but I don’t know how to do that. Please also list any ideas for Google Map plugins

Mappress allows for custom markers, but you need to pay for the pro version.
http://wordpress.org/extend/plugins/mappress-google-maps-for-wordpress/

Google Map Shortcode also supports custom markers in a shortcode
http://wordpress.org/extend/plugins/google-map-shortcode/

Getting custom overlays on Google maps is actually pretty easy, you can read the docs here if you choose to work directly with the API, http://code.google.com/apis/maps/documentation/javascript/overlays.html

There are plenty of options here: http://wordpress.org/extend/plugins/tags/google-map