If you have a website, you want to get traffic to it. One way to do it is to leave comments on related blogs using your keyword as Name; and your real email address and the URL of your website.
Leaving comments on a blog will most likely give you a backlink (if it gets approved by the blog’s owner) to your site, thus increasing your site’s chances of getting closer to the first page of Google or other search engines like Bing or Yahoo. Why is that important? Because the closer you are to the first page the better is your chance that someone will find and visit your site.
If your comment does not get approved by the owner of the blog, you don’t get a backlink either, regardless of your comment. So why waste your time just to have your comment deleted?
Scan the articles quickly if you are doing it just for backlinks and don’t care about the subject and leave a related comment and BAMMMM You’ll get a backlink to your site.
Like this blog for an example. I get many comments and more than 3000 of them in the last six months was deleted. 3000 fruitless efforts from people trying to get a backlink. Waste of time. The comments I approve are might not be related all the way, but at least they show some effort. From time to time I also go back in the comments and delete some, if on the second thought I think they are more spammier.
I am willing to help people to get backlinks from this blog and let some junk through, but there is a limit have to be established.
You should not include an html address in the body of the comment because it will get deleted. Html address (web address) belongs in your signature (Name-email-website). Unless perhaps if the comment expands on the subject. Like linking to an authority site like Wikipedia or CNN News or whatever authority.
If you don’t think the blog’s owner should benefit from your comment, than don’t expect anything in return.