In another post i showed how i installed ProjectM (The Open Source Milkdrop for Linux)
It has just been sitting dorment wasting hard drive space, now to tie it in with Amarok
Get the Source code from Sourceforge projectM website labeled (ProjectM-LibVisual)
Extract the code.
I needed an extra package
sudo apt-get install -y libsdl1.2-dev
then cd into the source directory and run
cmake . -DCMAKE_BUILD_TYPE=RELEASE
Nom when you click visualisations in Amarok you will get ProjectM
Diego has just pointed out that ubuntu now has packages to support Project M in amarok.
See his comment for details