This is a nice demo of how to have a PHP script create a graph with Gnuplot. The source code for this file is available.
Number of servers to show on x-axis Monthly hosting cost, per 1U
Price of a Chip-class box # of gameservers per chip Height of a Chip-class box
Price of a blade chassis Price of a blade # of blades per chassis # of servers per blade Height of a Blade chassis