wacrgEIS is software developed for the West Australian Corrosion Research Group (wacrg) for analysis of electrochemical impedance. At the moment it consists of: equivcctfit, kramkron, simulate, fixscoc, splitimpedances, tabulatenets and z2bouk:
The advantages of wacrgEIS over other impedance analysis software is that it is strongly batch oriented; its open source; and its free.
The disadvantage: there is no fancy GUI. You have to find your own means of plotting results. GNU Plot is a good option, or you can use a spreadsheet.
wacrgEIS is only available in source code form at the moment, which means you need a C compiler and a few other libraries (libGSL and PGAPack, see BUILDING.TXT in the source distribution.) You can download the source code from here. You can also visit the the project page on Sourceforge.If you want to compile for Windows, you'll need to install Cygwin, or else do a little porting of the code to compile with mingw32.