It is just up to Google! I have a site from 6 years now and recently Google put the special links on the search result of it. It's a Google Black Box calculation!.
Logically it depends of the amount of pages indexed, the amount of results related, SEO optimization and.........a lot of patience
They're called Sitelinks. This is what Google itself says about them: How does Google compile the list of links shown below some search results?
Also have a look at Matt Cutts' short presentation about the anatomy of a search result.
Vanessa Fox provides the most detail about how they work and what you can do to influence them.
Google auto-generates them, based largely on easy-to-crawl, relevant, internal links with short titles on your site's homepage. They'll only appear on the first search result, and only when Google thinks they're useful. There can be up to 8 sitelinks.
As the Google support page also says, you can view them for your site in their Webmaster Tools and block those ones you don't like. You can't add any yourself.
A recent Webmaster Central blog post adds that a single row of up to 4 sitelinks can appear on more results than just the first one now.
There is no way to select which pages on your site are used as site links. You can however register as another person said for Google's Webmaster Tools and block site links that may be displayed for your site until it gets around to showing the pages that you want it to. I have noticed that Google seems to display sitelinks for larger sites.
When you do choose to block URLs from appearing as site links it is important to know that they do not stay blocked for ever. They have a block expiry date on them, so you would need to monitor this.
that are special links shown by google in search results which are helpful to user. That are created by google when your site is very informative and well optimized.
regard's Sachin kalambe