Have a blog? Link to it, copy it here, or just write it here. You’ve got readers.
Need help? Find a writing partner. Ask a question. You’ve got experts.
Need exposure? Customize your “My Page”. You’ve got publicity.
And, most importantly, invite your writing friends. (Don’t just invite your Uncle Charlie...unless his last name is Kaufman.) The value of a social site depends on the quality of people involved and their commitment to helping others.