Optimal Switching models are concerned with sequential decision making where the controller has a finite number of policy regimes. Such models arise naturally in pricing of energy assets, including tolling agreements for electricity production, natural gas storage facilities, carbon emission permits, etc. I will discuss the general mathematical structure of optimal switching models, including their relation to multiple stopping problems. I will then describe some work in progress with R. Sircar on exploration control in exhaustible resource management. In the second part of the talk, I will focus on numerical methods and implementation issues for optimal switching, especially simulation tools that extend Monte Carlo methods for American options.