I know that a lot of the best forums have gone nofollow. I found this cool squidoo lens with a DoFollow Forums List and would like to share it with the Digital Point Community. There are some really cool forums in there, as always lets try to add some value to forums and not just spam them to death.
Hello Friend, Here you can find more than 100 dofollow forums list.. http://www.adsportal.in/useful-seo-resources/dofollow-forums-list/
What's the point of using forums for backlinks? You can get much more link juice using just high PR pages.
I have one too, just for sharing http://www.iamkaiser.com/list-of-dofollow-forum-that-accept-anchor-texturl-in-signature/