QaSimDemo
Offers qualitative analysis to verify which circuit structure is suitable for a given purpose. Also in German.
www.nst.ing.tu-bs.de/schaukasten/qasimdemo/en_idx.html
APLAC Analog Circuit Simulator Tutorial
A general purpose nonlinear circuit, system, and electromagnetic FDTD simulation and design program.
www.aplac.hut.fi/aplac/cookbook/main.html