What is the purpose of the clear windows in some helicopters in the floor of the nose, right where the pilot's feet and pedals are?
For example, here's a Huey with windows clearly visible:
Airbus helicopter example:
These fall into a category known as vertical reference windows. They can be used for many purposes, but essentially, they allow us to gain a better spatial picture of the orientation of our aircraft, the skids, and anything that might be slung beneath the aircraft. As someone who has landed many helicopters on trailers, it is extremely helpful to be able to see through the floor when precisely placing the skids. Holding a pinnacle approach and hover is much easier to execute as well. Further, when you have something on a line, it makes it easier to keep it in view, especially when it is closer to the aircraft.