Website Directories
Site directories are much like traditional business directories except for hyperlinks. They can include links to commercial, informational, educational institutions, and non-profit websites. The links are categorized into different high level taxonomy and then taken to the most specific description of the website. The Yahoo! Directory and Open Directory Project , Dmoz.org were two of the earliest lists of links which turned into a basses for many search engines' results.
Other examples include: Business.com, Joeant.com, Best of the Web (BOTW.org), Sevenseek.com
Adding a website to directories is a common and well know method of increasing a website's backlink popularity, which in turn helps with search engine rank.