In case you do not know what you can do with DTrace, take the time to have a look at the DTrace blog. It is worth any minute you invest reading it.
Today I stumbled again over some HeatMaps from Brendan Gregg (of DTrace–fame). This time it was the PDF of his presentation at the LISA 2010 conference. It shows nicely how he plans to evolve it from a single-machine (like in Analytics for Oracle Storage products) to the cloud. It is a very good overview about what kind of intuitive performance visualization you can do with this.
I would love to see something for FreeBSD (or other performance data). Maybe someone could take the DTraceTazTool as a base or hint and write something generic which works for a lot of things…
There are just too much nice and interesting things out there, and not enough time for all of them.