Heatmap

<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/gh/simplegeo/polymaps/v2.2.0/polymaps.min.js"></script>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/gh/mbostock/polymaps/586fbb0346548a5559b6edea8aab76ac51334da5/lib/crimespotting/crimespotting.js"></script>
    <style type="text/css">

@import url("https://cdn.rawgit.com/simplegeo/polymaps/v2.2.0/examples/example.css");

html, body {
  height: 100%;
  background: #E6E6E6;
}

svg {
  display: block;
}

</style>
  </head>
  <body>
    <script type="text/javascript">

var po = org.polymaps;

var svg = document.body.appendChild(po.svg("svg")),
    defs = svg.appendChild(po.svg("defs")),
    rg = defs.appendChild(po.svg("radialGradient")),
    s0 = rg.appendChild(po.svg("stop")),
    s1 = rg.appendChild(po.svg("stop"));

rg.setAttribute("id", "gradient");
s0.setAttribute("offset", "0%");
s0.setAttribute("stop-color", "green");
s1.setAttribute("offset", "100%");
s1.setAttribute("stop-color", "green");
s1.setAttribute("stop-opacity", 0);

var map = po.map()
    .container(svg)
    .center({lat: 37.787, lon: -122.228})
    .zoom(12)
    .add(po.interact());

map.add(po.image()
    .url(po.url("https://{S}tile.cloudmade.com"
    + "/1a1b06b230af4efdbb989ea99e9841af" // https://cloudmade.com/register
    + "/998/256/{Z}/{X}/{Y}.png")
    .hosts(["a.", "b.", "c.", ""])));

map.add(po.geoJson()
    .features([
  {geometry: {coordinates: [-122.258, 37.805], type: "Point"}},
  {geometry: {coordinates: [-122.248, 37.805], type: "Point"}},
  {geometry: {coordinates: [-122.258, 37.815], type: "Point"}}
])
    .on("load", load));

map.add(po.compass()
    .pan("none"));

/** Post-process the GeoJSON points! */
function load(e) {
  var r = 20 * Math.pow(2, e.tile.zoom - 12);
  for (var i = 0; i < e.features.length; i++) {
    var c = e.features[i].element;
    c.setAttribute("r", r);
    c.setAttribute("fill", "url(#gradient)");
  }
}

</script>
    <span id="copy">
      &copy; 2010
      <a href="https://www.cloudmade.com/">CloudMade</a>,
      <a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors,
      <a href="https://creativecommons.org/licenses/by-sa/2.0/">CCBYSA</a>.
    </span>
  </body>
</html>

Updated missing url https://cdn.rawgit.com/simplegeo/polymaps/v2.2.0/polymaps.min.js to https://cdn.jsdelivr.net/gh/simplegeo/polymaps/v2.2.0/polymaps.min.js

Updated missing url https://cdn.rawgit.com/mbostock/polymaps/586fbb0346548a5559b6edea8aab76ac51334da5/lib/crimespotting/crimespotting.js to https://cdn.jsdelivr.net/gh/mbostock/polymaps/586fbb0346548a5559b6edea8aab76ac51334da5/lib/crimespotting/crimespotting.js

https://cdn.rawgit.com/simplegeo/polymaps/v2.2.0/polymaps.min.js

https://cdn.rawgit.com/mbostock/polymaps/586fbb0346548a5559b6edea8aab76ac51334da5/lib/crimespotting/crimespotting.js