DMOZ or the Open Directory Project (ODP) is the largest directory of websites with around 5 millions sites listed. It is owned by AOL but operated by a large group of volunteers. There are many who believe that it is important to be listed in DMOZ as it can help a ranking for the website in the search engines. It is probably not a big factor these days, but many webmasters are desperate to get their sites listed in DMOZ.
http://www.seo-101.com/dmoz-or-open-directory-project/4/ (SEO 101)
http://www.searchengine-faq.com/do-i-need-a-listing-in-dmoz-to-rank-well-in-google/ (Search Engine FAQ)