Have you considered a section on Frequently Asked Questions? There are so many great lessons that Lazarus and others have given that are so helpful in clearing up otherwise confusing aspects of the Spanish language. "Estar vs. Ser", "Por vs. Para", direct and indirect object pronouns are just of few that I remember reading.
HI Dr and Toph, we actually have a FAQ thread. Have a look here.
We actually do have a new category that might at least sort of serve the role you describe. The old Reference section is now an Answers category--except that, instead of contributing questions and answers, users all work to improve a single definitive reference article.
(notice that all old reference articles are now here)
Unlike, say, Wikipedia, we don't want the editing of reference articles to be open to everyone. Instead, only users with reputations of at least 5,000 (e.g. Lazarus) may create and edit reference articles.
What do you think of that?
Also, if you love a question or answer or reference article, make sure to vote for it. That'll help it surface higher in search results, whether in Answers itself or when people look up a word in the dictionary. With luck, the most frequently asked questions will naturally be the most discoverable.