--- a
+++ b/modules/HTTPRequest/playground/histogram-chart.js
@@ -0,0 +1,83 @@
+function histogramChart() {
+  var margin = {top: 0, right: 0, bottom: 20, left: 0},
+      width = 960,
+      height = 500;
+
+  var histogram = d3.layout.histogram(),
+      x = d3.scale.ordinal(),
+      y = d3.scale.linear(),
+      xAxis = d3.svg.axis().scale(x).orient("bottom").tickSize(6, 0);
+
+  function chart(selection) {
+    selection.each(function(data) {
+
+      // Compute the histogram.
+      data = histogram(data);
+
+      // Update the x-scale.
+      x   .domain(data.map(function(d) { return d.x; }))
+          .rangeRoundBands([0, width - margin.left - margin.right], .1);
+
+      // Update the y-scale.
+      y   .domain([0, d3.max(data, function(d) { return d.y; })])
+          .range([height - margin.top - margin.bottom, 0]);
+
+      // Select the svg element, if it exists.
+      var svg = d3.select(this).selectAll("svg").data([data]);
+
+      // Otherwise, create the skeletal chart.
+      var gEnter = svg.enter().append("svg").append("g");
+      gEnter.append("g").attr("class", "bars");
+      gEnter.append("g").attr("class", "x axis");
+
+      // Update the outer dimensions.
+      svg .attr("width", width)
+          .attr("height", height);
+
+      // Update the inner dimensions.
+      var g = svg.select("g")
+          .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
+
+      // Update the bars.
+      var bar = svg.select(".bars").selectAll(".bar").data(data);
+      bar.enter().append("rect");
+      bar.exit().remove();
+      bar .attr("width", x.rangeBand())
+          .attr("x", function(d) { return x(d.x); })
+          .attr("y", function(d) { return y(d.y); })
+          .attr("height", function(d) { return y.range()[0] - y(d.y); })
+          .order();
+
+      // Update the x-axis.
+      g.select(".x.axis")
+          .attr("transform", "translate(0," + y.range()[0] + ")")
+          .call(xAxis);
+    });
+  }
+
+  chart.margin = function(_) {
+    if (!arguments.length) return margin;
+    margin = _;
+    return chart;
+  };
+
+  chart.width = function(_) {
+    if (!arguments.length) return width;
+    width = _;
+    return chart;
+  };
+
+  chart.height = function(_) {
+    if (!arguments.length) return height;
+    height = _;
+    return chart;
+  };
+
+  // Expose the histogram's value, range and bins method.
+  d3.rebind(chart, histogram, "value", "range", "bins");
+
+  // Expose the x-axis' tickFormat method.
+  d3.rebind(chart, xAxis, "tickFormat");
+
+  return chart;
+}