No matter how good your site's navigation is, the fastest way for your visitors to find exactly what they're looking for is for them to search for it. You can choose between a free ad-based service and the Professional Service with more features and no ads. Set up takes less than five minutes. Their study finds that instead, people tend to use the site's name as a search term. Other studies have said that search engines and links were the two most important ways people find your site.
More people come from there than any other source.
So this means that getting into Yahoo is clearly important. Unfortunately, it's also clearly more difficult than the others. Yahoo has real people who adds sites that people ask them to add. Yahoo gets tens of thousands of listing requests per day, and this is why it's taking them longer and longer to add sites. But this can mean a real disadvantage for your new site or event.