I have seen these being used every which way, and have been accused of using them the wrong way (though in that case, I was using them that way to demonstrate a point).
So, what do you think are the best practices for employing Extension Methods?
Should development teams create a library of extension methods and deploy them across various projects?
Should there be a collection of common extension methods in the form of an open source project?
Update: have decided to create an organization wide extension methods library