Oracle's APEX ships with some great plugins such as D3 Collapsible Treemaps. The most immediate way to see these is to install the Sample Charts application and have a play with it.
Now it is then fairly striaghtforward to utilise this plug-in in your own APEX applications. Here I simply exported the plugin from the Sample Chart applications and loaded it into my new application. I then changed the SQL to drive from my own tables and here we are. What is appealing about this visualisation is that it shows the number of children under each node before you click to expland. For example, here I can see that 1200 has 5 children underneath it.
I have also used the "Tooltip" funtionality to give me a nice popup description when I "Mouse-over" the node.
Also each node can be made as a link that can drill off to show the user further detail, so it does really become quite a useful visualisation that can be used quickly and easily.
The Sample applications that ship with APEX ( and I'm currently using the latest 5.1.1 ) come with quite a few plugins that show off the extensibility of the framework and should give you some ideas on how best to use them, so if you are upgrading from older versions of APEX and making the leap to 5.1 then i'd highly recommend installing selection of the applications and see what's been shipped there. Of course this is the release that has finally integrated JET charts and we will cover some of their use and examples such as drilling to detail in a later blog.