GGobi is an interactive, direct manipulation tool for visualizing
high dimensional data across linked plots.  It provides highly dynamic
and interactive graphics such as tours, as well as familiar graphics
such as the scatterplot, barchart and parallel coordinates plots.
Plots are interactive and linked with brushing and identification. The
GUI is built using Gtk+.  It reads data in regular ASCII format and
more richly using an XML format.  Plugins for other formats are also
available.