Jeff,
One thing that we/you could think about doing to really take things up a notch is to invite an author on every so often to discuss their (new) book. You need a host. It takes about two hours. And you end up getting a thread of 150 or so comments. You have a preview thread a month in advance. It is not essential that everybody has read the book. The host must read it and lay out the main points for discussion and pick up the slack if their aren't enough questions from the audience. The only thing that might be difficult is ensuring that you have enough of an audience. I participate in some on other forums and they are great. If you have at least 20 people who are willing to actively participate it would work. It would really increase visibility. I'm not positive about classicists being willing to participate. They usually get a $500 stipend plus expenses to go give a talk at a university. The other forums that have them usually find eager authors because they are selling topical books and really want to increase buzz and thereby sales. Classics not so much a sales business. Still worth seriously considering.