Directory submitting service can provide that your site will be viewed by sites that have back links to and from your site to their site to the your site's Google popularity. Adding yoru stie to other websites, it is as important as unique content as they are both loved by serach engines such as Yahoo and Google.
If you really want to get free backlinks without having to shell out some money to pay for a directory submission service provider's fee, you can do your on submissions and your own research and your own optimization. There are numerous web directory lists on the internet that you can get links and backlinks from simply by submitting your website for consideration. While these are indeed free, these link applications to directories on your own may take too long with all the websites asking for free links to these directories. Utilizing a directory submission service for this purpose not only assures you of quality links and backlinks at a reasonable price, but also gives you the peace of mind that your site has indeed been linked to the directories that matter. In essence, paying the small fee to get yourself a sure link and backlink to and from these directories is almost like it being free since the number of directories you will be linked with will assure you of a significant increase in traffic sooner than you would have if you did it yourself.