Collecting some examples of less obvious, more niche mental models:

Live players and dead players (Burja)

Definite vs Indefinite Optimism

Toy projects can generate valuable outcomes

Institutional memory and amnesia

Offensive vs defensive infrastructure

'Luxury beliefs' are latest status symbol for rich Americans

Pace Layers & Long-Lived Institutions

Class 1 / Class 2 Problems

These are in addition to well-known generic mental models (e.g. Pareto principle) as described here:

Mental models must be made operational