As of Version 6.0, ColorOutput has been superseded by ColorFunction, ColorData, and related functions.
ColumnForm has been superseded by the more general function Column.
As of Version 6.0, ContourGraphics has been superseded by GraphicsComplex and related functionality.
As of Version 6.0, ContourLines has been superseded by settings for ContourStyle.
As of Version 6.0, ConversionOptions is superseded by capabilities in Import and Export.
Date
(Obsolete Mathematica Symbol) Date has been superseded by DateList since Version 6.0.
As of Version 6.0, DefaultColor has been superseded by the more general option BaseStyle.
As of Version 6.0, DensityGraphics has been superseded by GraphicsComplex and related functionality.
Display
(Obsolete Mathematica Symbol) As of Version 6.0, Display is superseded by capabilities in Export.
As of Version 6.0, DisplayString is superseded by capabilities in ExportString.