Wow. I just found this pretty awesome TreeMap tool. The data format it reads is pretty easy and I quickly built a file with some of my firewall data. Well, fake firewall data 😉
What you see in here is first the color: green are firewall passes, red are blocks, then the hierarchy is such that the target system is top, then the target IP and then you see the date inside of the boxes, when the access happened.
Well, the tool is pretty awesome. Lots of interactivity. You define the hierarchies manually, on the fly it updates the graph. Then you can color and filter and all kinds of nifty things. Try it out.