Optimizing your site for search engines? Don't forget about DMOZ's Open Directory Project (ODP). Beyond being registered with the dmoz.org open directory project (which Google uses to obtain meta data about your site) be aware that Google uses the title and description from DMOZ's listing for your site in their search logic.

Google sometimes likes to construct the SERP (search engine results page) title from your page's title AND a bit of the first paragraph of text on your page.

But what if you want to override that description, for example, you want to optimize a page for keyword ranking? Enter the 'No ODP' tag:

Vanessa Fox notes over on the Sitemaps blog that Google now supports the META NOODP tag. What does this tag do? In some circumstances, Google uses descriptions from the Open Directory Project as the title and snippet for a web result; this tag lets you opt out of the ODP title and description.

Read more at Matt Cutts blog.

Want to understand more about how Google uses the ODP to build page titles, but only under certain conditions? Here is an article excerpt from SEO Roundtable that shows how Google shows different titles depending on search term used:

It is true, and its a pretty significant change on Google's part. ... The theory is that if the search matches the ODP listing, it will show it. So in my case, if you view the Google Directory (uses ODP) in the "/ Computers  / Internet  / Web_Design_and_Development / Designers / Full_Service / R /" section, and look at the 10th listing, you will see "RustyBrick" and the description. Both used in the main SERPs at Google when search on at Google, under "rustybrick".  

Some information and discussion about Google's use of the Open Directory Project: