Here is the list where you can submit your forums.

http://www.forumzilla.com
http://www.forumdir.com/
http://www.gandalfdir.com/
http://www.forumsinfo.com/
http://www.1001forums.com/
http://www.boardreader.com/
http://www.bbswatch.com/
http://www.forumshowcase.com/
http://www.forum-directory.com/
http://www.forum-search.com/
http://www.forumsearch.tk/
http://www.forumsindex.net/
http://www.foruma-z.com/
http://ipbdirectory.com/
http://www.domainers.org
http://www.forumhunt.com/
http://www.forumguide.info/
http://aforumblog.com/directory/
http://www.findyourforum.com/
http://www.forumsarchive.com/
http://www.onlyforums.com/
http://www.phnetforum.info/submit-site.php
http://www.bluenoser-forum.com/
http://forumpimp.star-killer.com/
http://www.forum-database.com/
http://www.forumrating.com/
http://www.quickthreads.com/
http://www.forumurl.com/
http://www.az-forums.com/
http://www.itch.com/infoforwebmasters.html
http://www.forumfeeds.com/
http://forum-directories.com/
http://www.forumfox.com
http://www.forumwebdirectory.com
http://forumcity.org/links/dir
http://www.forumdirectory.biz
http://www.allforumsdirectory.com
http://www.drupalsites.net/weblink/forumfinder
http://forumfinder.trendstoday.info
http://www.geocities.com/forumsearch
http://www.forumhaven.com
http://lookdirectory.com/forum

Hope you like it.

OMG this is Awesome.
Thanks Nameslot for Sharing this Huge list to us.
I will surely submit my forum to this list and will reply you with the SEO effect of this list. :)

you can also submit your forums on my site:

http://www.newdesignworld.com/browse-forums-35-1.html

NewDesignWorld.com