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.