I found a plug-in which make links by commenter’s Dofollow instead of Nofollow which is the default link type for WordPress. All you need is to upload the dofollow plugin from SemioLogic.com and activate it in WordPress Plugin Control Panel.
By making your links DoFollow instead of NoFollow, your commenters will also get more link juice. Some of your visitors will also be more likely to comment since they will get more dofollow back links to their website which increases their Search rankings in Google and other search engines. DoFollow is great for Search Engine Optimization.
Update: I decided to make this blog NoFollow again since I don’t have the time to moderate spammy comments and comments which are poor quality like people who post “thx” which I tend to be getting after I change this blog to DoFollow.
Download WP Dofollow plugin at  http://www.semiologic.com/software/dofollow/
This was really interesting, I really learned something different by reading it. Thanks and keep up the great work.
Do Follow blogs have a major advantage over No Follow blogs that is they are crawled by all search engines including Google. As Google’s bouts and robots do not scrawl no do follow blogs. Do follow blogs is useful for back linking from the SEO perspective. Thanks for the informative post both from general and SEO point off view.
Thanks for putting informative and helpful tips here. Expecting more from uu.
Wow I never realized how I might be hurting my blog by keeping it nofollow. I have a great plugin for killing spam, better than Akismet so I’m thinking I should make my blog dofollow and see what kind of response I get. Great info.
Yes, you can get more comments by making Blog comments dofollow, but be sure to moderate your spammy posts, and make sure commenters don’t link to spammy sites since this can also hurt your search ranking, and possibly make your advertisers like Adsense upset since some Adwords clients don’t like their ads on pages with spammy links.
Can you share the plug-in with us, Henry, on reducing spam with a plug-in?
Great information,very useful.Thanks for sharing.
Dofollow simply get too many opportunistic people out there spamming every article in your archive. Posting comments in nofollow blog can still be useful. For one, it is free advertising and two if you contribute something a bit more insightful than a simple ‘thx’ as Johnson pointed out, then it just might prompt a reader to follow the link to the commenter’s blog. Organic SEO