Earlier, Google realized that sometimes people want to go to a specific portion of a website, so they started populating “sitelinks” below certain search results. Sitelinks, are automatically-generated list of popular places from a site. The links are not always the best, but they might save you a click and some time spent on sites that are difficult to navigate.
Some sites include a lot of content and their search box is more important than a navigational menu. For these sites, Google has added another new feature called “site search box” below the sitelinks that allows you to restrict your query to the first search result. The search box shows up for a small number of sites like: Flickr, YouTube, Metacafe, Amazon, Craigslist, SourceForge, which makes you wonder if they were handpicked or automatically selected.
Google, Search, Web Search, Search Result, Search Box, Site Search, Yahoo!, Search Engine