There are plenty DoFollow Forums available over internet but I just compile all of them in just one post. I hope all of you love it.
I think that while it's important that you participate in do follow forums, it's equally important that the forum you're participating in is in the same niche as your site. Participating in forums is not just to build backlinks to your site. It is a way of building a reputation for your site as well. You will get more clicks to your site from the links in your forum posts if your fellow forum members know you're someone that can give them value or good information. Hope that helps. Have a good day!
My list of Do Follow Forums : http://www.squidoo.com/best-do-follow-forums I sort them category wise and according to PR
Link building on do follow forums with optimized anchor text is against Google TOS and could get your site penalized for over optimization. In other words, you should concentrate on relevant forums that have good traffic. To recap, forum link building to increase your rankings shouldn't be your goal, getting relevant traffic while building trust is more important IMO.
Here are some Do Follow Forums for you - Do Follow Forums List Forums Posting Service Package - Seo Manual Submission. This site was actually previously posted in this forum by another member. It is pretty cool actually because it gives you a pretty big list of forums. You can find a couple with very good PR and become active in them. Make sure they are related to you niche though. Do not just go and register for forums randomly. Be active.