Max FreeHand Tools
A set of tools - written as a MacroScript - that lets you paint curves and geometry over 3D Objects. (very similar to Maya Paint|Effects)...
Version 3.1 fixes the Illustrate! issues (thanks to Louis Cherry) - as well as a couple of UI problems for 3dsmax 4.2.
Scripters : be aware that the Brush Syntax has slightly changed.
Nature Brushes by Herman Saksono