This plugin supports multiple markers per map! Kudos to yohman for his plugin: http://wordpress.org/extend/plugins/google-maps-v3-shortcode/
Simple yet effective wordpress google map plugin to create unlimited maps with single or multiple markers.
Plugin for create your own markers on Google Maps, as a Custom Type posts, and with an easy integration on your page.
Location Click Map plugin is useful to display marker on clicking of location, use shortcode [location_map].
Multiple map marker and filter plugin is useful to display maps on your website posts and pages using shortcode [map_filter], With fully customized ic