List of 40+ High Page Rank Free Do-Follow Forums and Blogs

Link Building is a important part of Search engine optimization.These backlinks will be able to able to rank your page higher and improve your traffic from search engines.But not any backlinks will help you to rank your page higher.
Backlinks specifically from high PR blogs and forums will be able to get you a high page rank for your blog.Do Follow Blogs and forums encourage you to comment on their site by allowing the do follow attribute on their comment section and hence help you to achieve good high PR backlinks.
So here i have listed out 40 blogs and forums that have Do follow attribute to encourage commenting.Try to be active in these pages as frequently as possible to achieve constant good backlinks.
PR 9
http://www.flickr.com/help/forum/en-us/
http://www.addthis.com/forum/index.php
http://www.bibalex.org/a2k/Forum/Topic.aspx
http://quality.mozilla.org/forum
http://www.adjunctnation.com/forums/index.php
Pr 8
http://forum.joomla.org/
http://www.about.com
http://www.campusvirtualsp.org/
PR 7
http://www.bungie.net/Forums/default.aspx
http://www.sitepoint.com/forums/
http://forums.feedburner.com/
http://forums.mysql.com/
http://forums.cnet.com/
http://www.gamespot.com/forums/index.html
http://www.bookforum.com/
Pr 6
Mysql Forum
Deviantart
http://www.currybet.net/
http://www.tvhe.co.nz/
http://bbpress.org/forums/
http://blog.greens.org.nz/
http://forums.amd.com/
http://www.feedforall.com/forum/
http://www.dreamteammoney.com/
http://forum.newsgator.com/
http://www.midasoracle.org/
http://weblogtoolscollection.com/
http://www.zymic.com/forum/
Pr 5
Digital point Forum
http://forums.photobucket.com/
http://sayanythingblog.com/
http://forums.afterdawn.com/
http://www.wickedfire.com/
http://www.v7n.com/forums/
http://www.techsupportforum.com/
http://www.bloggerforum.com/
http://www.daniweb.com/forums/
http://www.bloggertalk.com/
http://forums.worldofwarcraft.com/index.html?sid=1
It might not be possible to stay active in many of forums or blogs.So its better to select about 4-5  key sites your blog is related to and try to stay active in those 4-5 forums or blogs.