Email discussion lists are useful for affiliates for two reasons. You can learn useful information while subtly promoting your business and building your reputation.
Forums and blogs [UPDATE: And social media sites.] have mainly taken over the role played by Internet marketing email discussion lists. One still going strongly is LED Digest.
The LED Digest (formerly LinkExchange Digest) is a real veteran on the Internet marketing scene. You'll see a wide variety of topics discussed. Discussion tends to ebb and flow as different topics appear, depending on the interests of members. The discussion list is moderated. I recommend you lurk and learn and see how things are done before you post. You can learn from the way some of the experienced marketers provide useful information while managing to sneak in a little plug for their businesses. Blatant advertising is rejected by the moderator, who won't put up with rubbish. The most effective posts genuinely help people. Membership is free. You can see the archives here: