Globally, mailing lists help you communicate with people of similar interests. Topics range from historical analysis of W.W.II literature to using PageMaker effectively. You'll find support groups, research groups and professional groups. If you are looking ahead to new career or just starting out in a new profession, a mailing list is a good place to garner information and exchange ideas. If you are facing a health crisis, see if there is a support group for you.
Mailing lists exist for almost any topic imaginable.
Locally, some faculty now have lists created for class discussions. In the Inventing America program, for example, each faculty member has their own mailing list, and these discussions are incorporated into the curriculum for the class. You will become the list administrator, and directions for maintaining the list will be e-mailed to you. There are a variety of resources available to you. You may have friends or colleagues with similar interests or professional fields.