Optimal units for physical quantities. Prefixes are implicit.
time: 1, m
energy: 1, 1/m, kg, Ry
speed: 1, c
charge: 1, faraday (mol e), e
mass: see energy
temperature: see energy

Ångström counts as 10^-10 m
so 1 Å = 2.997 microseconds = 5*10^30 J^-1 = 4.5*10^47 kg^-1 = 69.5 10^6 K^-1

Enjoy adding your own.