Recently there was a post in the Raspberry Pi Forum, http://www.raspberrypi.org/archives/5934#comments on how to access the GPU (Graphical Processing Unit)
This seems less well documented probably for reasons of trade secrets, but some examples using blobs exist. One of this is FFT, which is useful for spectrum analysis
To enable this, at least until the FFT becomes part of the standard Raspbian, we need to run a tool called rpi-update. This has to be installed, so the usual apt-get actions are required first:
apt-get update apt-get upgrade apt-get install rpi-update
rpi-update pulls in the git connections stuff as well, so this is a useful step to take before wanting to self-compile a kernel. Anyways, we can now run
rpi-update
and it will pull in the latest && greatest. Having done this, we must reboot before continuing.
Then look in /opt/vc/src/hello_pi/ and there are several graphical and other examples there that can be checked-out, including the FFT.