Steve Harris has written a large number of plugins for LADSPA compatible hosts (e.g. GLAME, Sweep and ecasound). The plugins available are:

amp, fast overdrive, overdrive (with colourisation), comb filter, waveshaper, ringmod, divider, diode, decliper, pitch scaler, 16 band equaliser, sinus wavewrapper, hermes filter, chorus, flanger, decimater, oscillator, gverb, phasers, harmonic generators, surround encoders and more.