<ace:gMapMarker> allows for the placement of a marker pin on the map of your choice. This pin is highly customizable, and can be used to show a wide variety of information via user made icons and titles
Options are set as name:value, and are separated by commas.
Relevant section of the Google Maps API: Map Marker
A few good example options are 'flat:true', which will remove the 3d 'shadow' from the marker, and 'draggable:false', which will force the marker into one position.