Newer list:
https://en.wikipedia.org/wiki/Radioactive_decay#One-decay_process
https://en.wikipedia.org/wiki/Hodgkin%E2%80%93Huxley_model
logistic function
Black–Scholes
https://en.wikipedia.org/wiki/Sethi_model 
von Bertalanffy growth equation

### Models

Simple, equation based:
- World3 (from limits to growth report)
- classic predator-prey (Lotka–Volterra)
- attractors
- that vegan paper
- whatever Fe is the minimal of (function of protons/neutrons? discrete)
- urban subsidized housing (thinking in systems)
- Pulse Tube Cooler
- Hodgkin–Huxley model for neurons
x Uranium Critical Mass (meh, too complicated)
- black body (thermal emission)
- compton scattering
- Schwarzschild Radius
- three-body, eg
  http://nbviewer.jupyter.org/github/pjpmarques/Julia-Modeling-the-World/blob/master/Three-Body%20Problem.ipynb

Not-Time-Oriented
- high-precision model for water (enthalpy, etc)

Economics:
- rent control
- supply/demand curve
- World3
- https://en.wikipedia.org/wiki/Category:Economics_models

Harder, Time/State Based:
- Schmitt trigger (hysteresis)

Environment/Energy:
- pretty much everything from Sustainable w/o Hot Air

### Non-Model (?) Equations
- logistic function
- statistical distributions
- volume or surface area of platonic solids

http://equator.memeschemes.com/equation/
https://en.wikipedia.org/wiki/Category:Equations

### Constants

<copy in constants page from review of particle physics data>

https://www.wikidata.org/wiki/Q173227 (physical constant)

### Units

https://www.wikidata.org/wiki/Q15088658 (measured value)