Upgrading from:

Graphics`FilledPlot`

Plot, ListPlot, and similar functions have new Filling and FillingStyle options.

Fill from a curve to the axis:

Version 5.2 << Graphics`FilledPlot`;
FilledPlot[Sin[x], {x, 0, 2 Pi}]

Fill between curves:

Version 5.2 FilledPlot[{Sin[x], Cos[x], Sin[2 x]}, {x, 0, 2 Pi}]

FilledListPlot was available in previous versions of Mathematica and is now available on the web at library.wolfram.com/infocenter/MathSource/6809.