The documentation for .NET’s Excel interop API at msdn.com seems rather sparse.
Does anyone know of more thorough documentation elsewhere on the web?
I am looking for something that would, for example, list and explain all the properties of a Worksheet object.
There is Microsoft’s documentation on the Excel object model. The .NET interop is, to the best of my knowledge, just a wrapper around this functionality.
Besides the link provided by @ig0774, you can also inspect the Microsoft.Office.Interop.Excel library directly. Add a reference to it in a project, right-click it > View in Object Browser (or even better, using Reflector), this will list every class and interface, with the methods, properties, etc… This is a good complement to the link above; the documentation helps in understanding usage, but the object browser will show you what interfaces are implemented, which is extremely useful in some places, like if you try to understand how to work with some events on the Application object.