2D / 3D Area Graph provides both Client & Server solution for adding area graphs
2D/3D Area Graph Applet Standard License is a free to try software. You can free download and try it for an evaluation period.
Archim 1.4
Archim is a program for drawing the graphs of all kinds of functions. You can define a graph explicitly and parametrically, in polar and spherical coordinates, on a plane and in space (surface). Archim will be useful for teachers and students.