Mine

    var chartsize = 54;    var features = [];    for(var i=0;i<4;i++){        features.push(            new OpenLayers.Feature.Vector(                    new OpenLayers.Geometry.Point( -13630365 + 10000 * Math.random(), 4543034 + 10000 * Math.random())                    , { img: "http://chart.apis.google.com/chart?chs=" + chartsize + "x" + (chartsize / 2 + 4) + "&cht=gom&chl=" + i * 25 + "&chco=00ff00,ffff00,ff0000&chd=t:" + i * 25 }                ))    }    var style = new OpenLayers.StyleMap({                               pointRadius: chartsize/2                             , externalGraphic: "${img}"                        })    var vectors = new OpenLayers.Layer.Vector("graphs"                    , { isBaseLayer: false                    //, displayInLayerSwitcher: false                    , projection: new OpenLayers.Projection("EPSG:4326")                    , styleMap:  style });    vectors.addFeatures(features);