Forums are the best way to gain backlinks. Include your URL in your signature and profile. Here are some do follow forums list :-
http://forums.invisionpower.com/
http://forums.searchenginewatch.com/
http://forums.xkcd.com/
http://mu.wordpress.org/forums/
http://www.dokeos.com/forum/
http://community.postnuke.com/module-Forum.htm
http://expressionengine.com/forums/
http://warriorforum.com/
http://affiliate-marketing-forums.5staraffiliateprograms.com/
http://forum.ableton.com//
http://forum.abestweb.com/index.php?
http://www.rcgroups.com/forums/index.php
http://codingforums.com/
http://forum.joomla.org/
http://forum.mambo-foundation.org/
http://discussions.virtualdr.com/index.php?
http://addictsports.com/baseball/#forums
http://www.affiliateseeking.com/forums/
http://www.affiliates4u.com/forums/
http://forums.amd.com/
http://www.bloggerforum.com/modules/newbb/
http://www.bloggertalk.com/forum.php
http://www.businesss-forum.com/
http://www.bzimage.org/index.php
http://www.capitaltheory.com/
http://www.clickbanksuccessforum.com/forum/index.php
http://www.clicks.ws/forum/
http://forums.cnet.com/
http://www.code4gold.com/forums/
http://forums.comicbookresources.com/index.php
http://www.seoers.org/BB/
http://forum.deviantart.com/
http://www.ddboard.com/forum/
http://www.discussnames.com/index.php
http://www.directoryjunction.com/forums/
http://www.dnforum.com/
http://www.dnlodge.com/forums/
http://www.dnscoop.com/forums/index.php
http://www.domainforums.com/index.php
http://www.dreamteammoney.com/
http://www.ecauldron.net/forum/
http://www.egadforums.net/
http://www.ewealth.com/index.php
http://filesharingtalk.com/
http://freewebspace.net/forums/index.php
http://www.geekvillage.com/forums/index.php
http://forums.gentoo.org/
http://goldentalk.com/index.html
http://www.gptboycott.com/forum/index.php
http://acapella.harmony-central.com/forums/
http://forum.hittail.com/phpBB3/index.php
http://forum.hot4s.com.au/index.php
http://www.hotsurfs.com/talk/index.php
http://www.htmlforums.com/index.php?
http://www.hyipstalk.com/
http://www.idnforums.com/forums/
http://software.intel.com/en-us/forums/
http://www.im4newbies.com/forum/index.php
http://www.clicks.ws/forum/index.php
http://iq69.com/forums/
http://talk.iwebtool.com/
http://www.lex224.com/forums/index.php
http://www.livejournal.com/community/
http://forums.microsoft.com/
http://www.moneymakergroup.com/forums.html
http://www.movie-list.com/forum/
http://www.moneyfanclub.com/
http://mygamebuilder.com/forum/
http://forums.mysql.com/
http://www.namepros.com/
http://forums.onlinebookclub.org/
http://forums.oracle.com/forums/main.jspa?categoryID=84
http://www.paganforum.com/
http://paymentprocessing.cc/
http://www.phpbb.com/community/
http://www.pokerbrb.com/forum/index.php
http://www.revenuesource.com/
http://www.submitexpress.com/bbs/
http://forums.seroundtable.com/
http://forums.seochat.com/
http://www.seoforum.net.au/seoforum/index.php
http://forums.seo.com/
http://www.seo-guy.com/forum/
http://www.sidetalkz.com/forums/
http://www.simplemachines.org/community/
http://www.siteownersforums.com/index.php
http://www.sitepoint.com/forums/
http://host218.hostmonster.com/suspended.page/
http://www.small-business-forum.com/index.php
http://www.startups.co.uk/6678842908486596004/forums.html
http://forum.staticsubs.org/
http://www.submitexpress.com/bbs/
http://www.talkfreelance.com/
http://forum.tattootattoo.info/
http://forum.textpattern.com/
http://www.thefreeadforum.com/vbull/index.php
http://www.thegreennation.com/forums/index.php
http://v7n.com/
http://www.thehyipforum.com/index.php
http://forum.triphp.com/
http://www.soundandalarm.com/car-speakers.asp
http://ubuntuforums.org/
http://w3seo.org/
http://www.webdigity.com/
http://www.webdesignforums.net/forumhome.php?
http://www.webdeveloper.com/forum/index.php
http://forums.webicy.com/
http://www.web-life.org/vb/
http://www.hostingforum.ca/
http://www.webhostingtalk.com/
http://www.webmasterforumsonline.com/
http://www.webmastershelp.com/
http://www.webmaster-talk.com/
http://www.webproworld.com/
http://www.webtalkforums.com/
http://forums.windowsforum.org/
http://forums.winamp.com/
http://www.wahm.com/forum/default.asp
http://www.internetbasedmoms.com/
http://forums.worldofwarcraft.com/index.html?sid=1
http://forums.xandros.com/
http://www.adobe.com/support/forums/
http://www.rcgroups.com/forums/index.php
http://www.internettablettalk.com/forums/
http://www.avforums.com/forums/index.php
http://www.head-fi.org/
http://www.radioreference.com/
http://thegreenbutton.com/
http://forums.macosxhints.com/index.php
http://www.computeraudiophile.com/forum
http://www.zuneboards.com/forums/
http://www.computerbanter.com/
http://www.techwatch.co.uk/forums/
http://www.mobiletechreview.com/
http://forums.photographyreview.com/index.php
http://www.highdefforum.com/index.php
http://christev.forumsland.com/christev.html
http://www.acorndomains.co.uk/
http://www.theadminzone.com/forums/
http://www.allcoolforum.com/
http://www.baseballtalkpro.com/forum/
Syntax to write Link in forums:- [url=anchor link][b]anchor text[/b][/url]