Most of my app ideas haven't come to fruition yet, simply because I have so many of them relative to free time. I add the worthy ones to my ToDo list, to be rediscovered by Future Me when the time is right. Here are a few of the apps on my list:

• Audio pulse simulation
• Phasor analysis of Reimann-Zeta function.
• Forces from inter-field operators.
• Audio time-frequency grid.
• Realtime audio spectrum.
• Visualization of Bessel function integrand.
• Image-to-gcode app for laser engraving.
• 3D model from laser line scan (I use a 3DP for this).
• Random noise in a harmonic tree model
• App for using a bare CCD as spectrometer.
• OpticsLab, puzzle game involving aligning ultrafast spectroscopy experiments.
• Repeated annihilation particle grids.
• Coupling between longitudinal and transverse modes at an interface.
• Particle combs: Forces in open vs closed scenario.
• Generative music, dynamical sound filters, etc.
• Can drafting accelerate the 2nd car? Wind tunnel.
• 2D DFT, DFT of tree shapes, etc.
• Filament formation (lightning).
• Excitons and charge pairs in a semiconductor.
• Reverb simulation. Reverb removal via holographic reconstruction.
• Convolving space with a simple machine.
• A social network for sharing and mutating simulations.
• A social network for training and competition of battle swarms.
• Fermat's Last Theorem: Exploring solution space over exponent.
• Generative version of networkresonator.php with inline LCR components.
• Space-filling line integration as approximation of FT.
• Random trees can be generated from white noise.
• confinement.php on a sphere.
• Mutual inductance of knotted coils.
• Effective forces from teleparallelism.
• Traffic simulation. Compression waves.
• Ballistic simulations with billiards.
• Whirligig model of charge repulsion.
• Split-step FT supercontinuum calculation.
• FROG trace from pulse.
• Hydrodynamic zeeman effect.
• Light-front picture of electron repulsion.
• Spiral of multiples platform game.
• Torque waves in 3D.
• Harmonic coupling of planetary atmospheres.
• Conversion of real numbers in an nD space to helicities.
• Hyperrotation.
• Fractal period contours in 3D. e.g. The metahelix.
• 2D FT of naive deBroglie representation of repelling electrons.
• The 2-particle torus.
• Rope aliasing.
• Evolution of military hierarchy.
• 2e repulsion in eternalistic dephasing picture.
• Fire simulator.
• Phase accumulation from a passing wave.
• Twisted reference frames for untwisting orbits.
• Anharmonic oscillator circuits for music generation.
• Visualization of the difference between f(g(x)) and g(f(x)).
• Harmonic structure as an unwrapped spiral.
• ...