I have a great affection for an email list at Elon University called tch-econ. It is maintained by Jim Barbour and archived at Washington University St. Louis by Bob Parks. "This is an e-mail based discussion list. The format is deliberate - this technology is most available to those at smaller schools and in remote areas of the world. Additionally, the subscribers have indicated that moving to a web-based discussion list, while more elegant, would be less useful since most of us do not take the time to actively seek out web conversations, but we do all read our email. To subscribe, unsubscribe, or send a message to the list (subscribers only may send messages), ... simply " go to the web page at http://www.elon.edu/econ/tch-econ/. (quotes from Jim Barbour's tch-econ web page).
Currently there are about 330 subscribers of which about 200 different authors have posted since 2002. Authors hail from about 35 states and 36 countries. (Thanks for the info Jim). This list is a valuable resource for your teaching. If you have a real interest in advancing your teaching and want a good crowd to hear and respond to your questions by all means subscribe. Just don't forget to respond to others' questions as well.