WP Google Maps is an excellent plugin for adding Google maps with advanced features to your WordPress site really quickly. The free version gives you some basic way to add icons, but I upgraded to the Pro version very quickly once I figured out how well the plugin works. That opened up a whole new set of features, including pictures and links in marker info boxes, as well as driving directions to marker locations. This is really useful to my visitors. To allow me to use this plugin on a few more sites, I have now upgraded to the Dev version. Highly recommended!