There are literally 100's of free directories out there that you can submit your website to, and build inbound, one way links to your website. But it really helps to follow several guidelines to get the most benefit from these free directories.
Rule #1: Read the rules
Most directories have a list of rules that your listing must comply with to be accepted. Some directories have a very particular set of specifications, and if your submitted listing does not meet them, it will be deleted without a second glance.
So it is in your best interest to read the rules. If a particular directory does not have a list of rules, you can probably use a set of rules such as:
1- Submit your homepage url only
2- No promotional language or keyword stuffing in the title & description
3- Submit to the deepest sub category possible
Rule #2: Anchor text
As with all inbound links, you want to strive to get your keywords in the anchor text of the links. With directories, you have an additional challenge, as many of them require that you use your official site name as your title. So you may have to compromise.
Rule #3: Vary your anchor text
Another general rule of link building that applies to directory submissions is to vary your anchor text a little so that the links do not look artificial to the search engines.
Rule #4: Use legitimate information
Submit your real name, email, etc when you submit your website. Your link is much more likely to be approved if you do. If possible, use an email address at the domain you are submitting. Many directories like this, as it indicates that you are the owner of the site.
Just follow these rules to build 100% free inbound links to your website with directory submissions. And of course, you can even start your own directory to build more back links, but that's another story all-together.