Documentation should describe the possible configuration options and how/when to use them

[DominicCronin]

As a starting point, we might consider annotating:
https://github.com/dd4t/DD4T.Core/blob/develop/source/DD4T.Utils/ConfigurationKeys.cs

It would also be helpful to have this in a wiki page that's easily findable from how-to articles etc.

[DominicCronin]

Siawash has already written about two of them here http://tridion.stackexchange.com/a/14753/129