Yes, forum posting can be a good way to get real, human visitors to your site, so long as you are helpful and the forum members are interested in your niche.
It doesn't help with SEO, however. Even if the links are dofollow, they're worthless.
Forum posting helps to generate good traffic for your website through signature links and posts. They help to increase the website popularity in search engines.
Yes, you can build more traffic as well as best quality backlinks through forum.You have to find forums related to your site and give proper answers without doing spamming.
You need to post on High PR and your blog/site niche related forum. It is also important to post valuable and informative post. It will help you to drive huge traffic from search engines.