Tecplot like IDL is common commercial package
	http://www.amtec.com/Product_pages/tecplot.html

Here is a free package
	http://www.gnuplot.org/

VTK is "by far the best client package" 
	http://www.kitware.com/vtk.html
	There is a book on this but first read Amazon.com reviews
	to see if its what you want.
	
One package built on VTK is
	http://www.arl.hpc.mil/SciVis/dice/
	The leader of this effort (Jerry Clarke) is a friend of mine

A good but specialized package from Bill Hillard
	http://www.ssec.wisc.edu/~billh/vis5d.html