Verilog - Code Gen

http://search.cpan.org/~wvdb/Verilog-CodeGen-0.9.4/CodeGen/Gui.pm
v2html (http://www.burbleland.com/v2html/v2html.html)
If you want to inspect the generated code, you need the v2html Verilog to HTML convertor and a controllable browser, I use galeon (http://galeon.sourceforge.net).
A Verilog compiler/simulator
To run the testbench, I use Icarus Verilog http://icarus.com/eda/verilog/index.html, a great open source Verilog simulator.
A VCD waveform viewer
To plot the results, I use GTkWave (http://www.cs.man.ac.uk/apt/tools/gtkwave/index.html, a great open source waveform viewer.