TclSpice is an improved version of Berkeley Spice designed to be used with the Tcl/Tk scripting language. The project is open-source (BSD license) and based upon the NG-Spice source code base with many improvements.
SPICE is a general-purpose circuit simulation program for nonlinear dc, nonlinear transient, and linear ac analyses.
Features and Improvements:
update: tclspice is now a part of ngspice and builds under its source tree http://sourceforge.net/projects/ngspice/files/ng-spice-rework/24/
Where: http://tclspice.sourceforge.net/ Documentation: http://tclspice.sourceforge.net/docs/tclspice_com.html