Mathematica has long set the standard for high-end technical graphics and visualization. Version 6.0 added many innovative options that brought automated aesthetics to a new level, introducing powerful new programmatic parametrizations of visual presentation, and allowing new forms of high-level control over the visualization pipeline.
RegionFunction — arbitrary 2D and 3D plotting regions
ColorFunction — general coloring based on coordinates, parameters, etc.
ContourLabels (modified) — automatic contour labels
MaxRecursion (modified) — full adaptivity in 3D, contour, density plots
EvaluationMonitor — ongoing monitoring of function sampling
PerformanceGoal — whether to try to optimize for speed, quality, etc.
NormalsFunction — full control over 3D surface normals
PlotMarkers — automatic distinctive rendering of points
InterpolationOrder — smoothing or stepping between data values in 2D and 3D
Joined — points versus lines separately selectable for each dataset
Lighting (modified) — extended to new types of light sources
ImageSize (modified) — generalized to allow flexible constraints, relative sizes, etc.
ImagePadding — padding to allow for labels etc.
Tooltip — add tooltips to any plot or data element