LADSPA plugins accompanied by some blurbs about motivation and approach, mostly centered around (but not in the least confined to) digital guitarist needs.

a 12AX7-based preamp emulation.

super-60 is a 'cheap' (in the computational sense) amp/cabinet emulation.

unmatched is another 'cheap' amp/cabinet emulation.

an older spiced 12AX7 analysis and a simple hard clipper.

You may want to read the GPL.