A new version of NVAPI is out. NVAPI is NVIDIA’s core software development kit that allows direct access to NVIDIA GPUs and drivers on all Microsoft Windows platforms.
You can download the latest free version of NVAPI HERE.
NVIDIA has also published a driver settings programming guide (PDF) that explains how to play with some drivers settings like profiles.
Welcome to the NVIDIA Driver Settings Programming guide. This document explains how the NVIDIA set of drivers handle preferences and how these features are exposed through the NVIDIA NVAPI interface. The NVIDIA Control Panel–provided with all NVIDIA drivers– allows the user to control the behavior of all the NVIDIA drivers in the system. But for those users who want a more in‐depth control of the preferences in the NVIDIA driver, as well as for those users that wish to write their own Control Panel, this guide is for you. It explains the basic principles that constitute the NVIDIA settings framework and details how to program using NVAPI in order to retrieve and change any setting.