Definitely I love forum posting. This is the best method to increase my knowledge as well as experience.
Indeed, but only on popular forums of course. Its a great way to keep in touch with like minded people. Also if you're an expert at something, its a decent way to share you expertise.
Gotta love the spam, you'd at least think they'd start picking a new topic other than "5 great SEO tips" or "What is a website?"
Forum posting is very interesting and informative resources for newbie who wants to learn a lot of new things in their respective field not just the link itself.