Almost all blog platforms by default are set up so that a “dead end” piece of code is inserted wherever there is a link in a comment, so that search engines will not “count” the link as they are crawling the internet. This was originally designed to help stop comment spam, but it doesn’t work. What it does is remove some of the incentive for your readers contribute to your site by commenting on your posts.
What can you do about it? Turn off “nofollow”. Show your commenters that you appreciate them. Spread the link love.
How? Depending on the blog platform you’re on, you can install a plugin (like this one for WordPress), or disable it (see this post if you’re a Moveable Type user), or modify your template (check this site for Blogger tips).
Turning off the “nofollow” on blog comments has become a sort of “movement”. Well, if we’re going to have a movement, we should have something to show our readers that we’re part of it, don’t you think? I’ve created some little “I Follow” logos that would work well for a side bar, and if you’ve written a post letting your readers know that you’ve turned off nofollow in your comments, you could link the logo to that post. I’ve also set up some quick CSS if you’d rather:
If you’d rather use just CSS - click here to open a separate page and then view the source to copy the CSS from. You can easily change the colors to fit in with your site.
source : randaclay