How much of a Writing Center

I have currently been pondering the idea of how much of a Writing Center's resources are aimed at which type of students doing some kind of writing. We have hand books in our center that amaze me sometimes at the specificity of their nature. Writing just for literature, or business majors or online or writing when an ESL student is involved.
Last week we had our the big cheese of our ESL department come in and speak and my view on ESL students since then has greatly changed, as well as the issues that I see they deal with and how we handle these issues.
I have been wondering how much of a Writing Center should go to helping language acquisition and how much of it should go toward Native English Speakers (NES)? I know that one of the fundamentally wrong things to do with an ESL student is to categorize them immediately and try to use a formulated plan toward them but I have just been playing with the idea of our resources that we do have and their relation to ESL students. I am fascinated by language acquisition and its affects on a student's writing. I'm also very interested in foreign language acquisition and native language acquisition and how the two differ.

But, my main idea I was wanting some feedback on from different WCs around the country was to see how they handled their ESL students and their needs and utilized their resources within their center and on their campus as well.