While doing Forum Posting, dont forget to add Signatures too.

Almost all good forums (and mostly webmaster) allows you to have signature links. Now I don’t think this will help you to get good serps rankings but can give you decent traffic if the links are related. For example, if you have a boating site than posting in boating forums with signature surely helps.

There are some really Big forums which have DoFollow for signature links like Drupal's forum and Adobe's community.

Tips – You can find threads which rank high on serps and post a nice reply, so you may get traffic from serps as well. But don’t bump dead threads or don’t spam. Always follow community rules.

DigitalPoint has a nice list of forums which allow signatures. Use it but don't spam.