ArunKumar, Content is King. You can get a army of links to make your king strong. I would have to say that the most effective linking method is content inlinks. Links from blog content and website content are effective. The fastest and the most strongest way we use now is social bookmarking. Social bookmarking comes under web2.0. The reason why this seems to be effective is because we can post an intersting title which include our keyphrase so that we get the anchor text link from social bookmarking and social networking sites. The important thing to keep in mind is that build your links in a steady manner. Making lot of links in a small time is not what is expected from SEO point of view. Build strong and relavant links in a steady manner.
Press release is usually used to gain more traffic and it is issued for new products/services. Links from Press Releases have lot of limitations. Directory submission has lost its importance except niche directories. Videos and slides can't give strong backlinks.