I saw this on one of the stompbox Facebook pages:
Spectrum Software has closed up and released their Microcap simulation software free:
http://www.spectrum-soft.com/demo.shtm
http://www.spectrum-soft.com/download/download.shtm
I have not used it yet, only downloaded. But, apparently it is quite useful.
That looks cool!
For basic simulations including oscillograms and spectral curves, I use Caneda. It is Open Source freware.