There are a few old packages that allow the creation of x-y scatter plots from attributes in vector data
(Scattergram for 1.7) http://plugins.qgis.org/plugins/scattergrammidentify/
(SPQR for very early editions) http://www.maths.lancs.ac.uk/~rowlings/Software/Spqr/
But does anyone know of a package for 2.0 that would do this? or a way to rig up the old ones?