I guess this is a question whose answer is very difficult to find You might find this useful, from Matt Cutt's blog: http://www.mattcutts.com/blog/ui-fun-better-snippets/
You can try check this page about Google sitelinks as well. But good domain name and content matching search phrase and being #1 in search results, sitelinks are almost ensured in my experience.
Really a good question .But i think no need to bother about all those things if you have good content. Google will automatically crawl your web.
Sitelinks are links to a site's interior pages. Not all sites have sitelinks. Google generates these links automatically, but you can remove sitelinks you don't want.
i dont think that anybody know for sure how to achive sitelinks, but im guessing that a good domain name, unique content and a good source of traffic will produce sitelinks in good time.