Unless you’re lucky, you have heard of Facebook and twitter and other social media sites. As intrusive as these phenomenons are to people’s personal lives, they are great tools to promote your ebook. For every follower and friend you exponentially grow the possible number of future customers.
Facebook fan Pages are a great way for people to share with their friends your brand (check out mine here). There in addition are great social plugins you can use on your website to let people share individual pages (like your ebook) with their friends. In addition Facebook ads are an inexpensive way to get the word out as well. (Google adwords are good as well).
Twitter is a great way to network with people with similar interests. You might not get as many customers (unless your ebook is technical in nature) but you will get connected with people who can help promote your product through their own social network, or introduce you to products and resources to help you achieve your goals. Hint - Hashtags (#) and retweeting for your followers will help you gain more followers as will products like tweetadder. Several other things to keep in mind are the quality of your followers (and who your following), what you tweet about (how helpful it is to people), your ratio of followers to following (try to keep your followers relatively close, within a few hundred of the following) and when people are on twitter (usually when they arrive at work, after returning from lunch, and before they leave work).
As mentioned in the post for choosing a website (view here), getting found on search engines is important. Social media helps with that as well, the more people you drive to your website the more it helps your rating (in theory).
Getting listed on bookmarking sites helps as well. The most popular bookmarking websites are Digg, Delicious, StumbleUpon, Reddit, and Mixx. Using tools like Socializer and Social Media Add-On for Firefox can help with getting you exposed. Making the front page of one of these sites can REALLY get more visitors.
For more information here is a website i found online that could help TheSaveyBookMarketer