I know there exists already a post, describing nearly the same, but I think mine is a bit different.
What I would like to know is how you organize your extension methods
We put them all in their own namespace Company.Common.Extensions
. That way, if you have any of our extension methods, you have them all. Plus, at least at my shop, we don't have to worry about our developers not knowing about extension methods. I have the opposite worry, extension method overload! :)