I’ve been working with Highcharts a bit and they recently came out with a pretty cool Treemap chart. Here is a JSFiddle of a treemap that has a breadcrumb-style navigation (Treemap comes with a built-in navigation button, but it’s not super customizable). I built this one using BackboneJS.

http://jsfiddle.net/roblacy/4sb8vb1m/

The data comes from my cupcake post from last year and shows a breakdown of the number of free cupcakes that have ganache (instead of frosting) by day of the week each month.