Great question! My list: -Freq/pitch spectrum display of highest quality -Pitch detection algorithm -Formant detection alg. -Pitch drawing (in Audacity, over waveform and freq spectrum displays) -Pitch curve editor (a spline curve approximating the pitch) -Cepstrum display to Audacity (a requested feature) -Audio comparison alg. (melody matching at audio signal level only, not MIDI) -Antti's Moog filter (see music-dsp list) -Parameter interpolation to my Theremin app (see gmpi and music-dsp on zipper noise) -Replace the sampled allophones with a formant tonegenerator in my Allo speech synth -Drum synth -Write GUI widgets for graphically manipulating filter parameters (see Waves, Izotope) These all are quite small projects, but we all could work together. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software