In some relatively rare cases, Google will make use of the Open Directory’s headline for a page. Similarly, if a page lacks a title tag, Google may create a listing title by looking at common text used to link to that page. Additionally, Google sometimes decides to craft a listing’s title by combining text from a title tag, text from links, text from the page, the domain name or other methods that it decides is best.
As a site owner, I hate this. I want Google to use whatever page title I give it. Google argues back that it has to be creative, especially in cases where people have failed to provide titles. I’ve argued in the past that as a solution, Google should provide site owners with some type of “yes, I’m really really sure” meta tag to declare that they absolutely want their pages titles to be used. I’ve not won that argument. But, at least, Google will obey the NOODP meta tag and not use Open Directory titles, if you object to that.