Toolkits are collections of application-specific functions that extend matplotlib.
Plots data on map projections, with continental and political boundaries, see basemap docs.
mpl_toolkits.gtktools provides some utilities for working with GTK. This toolkit ships with matplotlib, but requires pygtk.
mpl_toolkits.exceltools provides some utilities for working with Excel. This toolkit ships with matplotlib, but requires pyExcelerator