Ngspice project aims to improve the spice3f5 circuit simulator.
ngspice on KDE (Linux)
ngspice running on Windows XP compiled with MinGW
ngspice on Sun-Solaris compiled with gcc
ngspice running on MacOSX (nedit is the external editor)
Ngspice running on Windows XP within Cygwin
ngspice on KDE (Linux) with gschem in background