But it's not always appropriate to talk about everything. Here are some guidelines. It may also be wise not to discuss your illegal activities either. Besides potentially affecting the well being of the list, you really don't know who may be listening in on an open and archived mailing list. Some posts have even been found indexed in the major search engines.
Discretion is a good thing.
Try to keep from getting into flame wars and overly personal discussions on the list. Flame wars have been the most destructive to the list community over the past few years. Some comments are probably better kept to personal mail. Keep in mind that what you are sending to the list you are sending to everybody. Other than that, go for it.