Twitterfeed is a quick tool to automatically Syndicate Content from your Blog / RSS feed to Twitter
Twitterfeed.com is completely free and too easy:
Step 1, just enter the URL of your blogs feed, Step 2 just tick your Facebook or Twitter Account and Done.
Another reason to use WordPress is it SO EASY to hook up to any of these social networks as any WordPress blog automatically has an RSS feed, just put that into Twitterfeed.
Twitterfeed publishes new posts to Twitter and Facebook as well, its so simple to set up, you can specify how often to post, how many posts to make, can connect to bit.ly and link shorteners and they have improved it lately too it will even post full proper Facebook Links with the image preview.