Writing has always been the beating heart of online user experience. It is also the single aspect of creating online user experience that designers and developers almost never study, discuss, or consider when tasked with creating a website—except perhaps to ask when the copy will be ready.
Issue 242 of A List Apart has just been published with two great articles on that oft-forgotten tool of the user experience, the writing. Better Writing Through Design by Bronwyn Jones and Reviving Anorexic Web Writing by Amber Simmons.
You owe it to your users.