gEDA : ACS - ACS is a general purpose circuit simulator. It performs nonlinear dc and transient analyses, fourier analysis, and ac analysis linearized at an operating point. www.geda.seul.org/tools/acs
gEDA : Icarus Verilog - Icarus Verilog is a GPLed Verilog Compilation System. www.geda.seul.org/tools/icarus
Homepage of gEDA - Gnu Electronic Design Automation tools. www.geda.seul.org