You can use this list:
Twitter - the best Social media communication website.
Stumble - the best social bookmarking website
Digg - it is not as good as it used to be before, but still very good.
Facebook - nice way to bring continuous traffic on your website
Traffup.net - Not just bring massive free traffic, but also free twitter followers and retweets.
Linked In- Great for niche marketing
Reddit - it is not as good as stumble, but sometimes bring amazing traffic.
Hubpages - Great way to get continuous traffic and backlinks.
Youtube - Create an attractive video of your website and promote it virally (if you are lucky)
Ycombinator - Good bookmarking websit