Image via CrunchBase
Import your blog to Facebook. Follow these instructions to add your blog to your notes page and include blog updates as part of your profile page activity. http://www.ehow.com/how_2031202_import-blog-facebook.html
Post your tweets to Facebook or use Facebook to post to Twitter by using the Twitter application in Facebook. The application is made by Twitter and seamlessly joins the two applications together so that one updates the other no matter which one you choose to use. Get more here:http://www.insidefacebook.com/2009/01/22/how-to-sync-your-twitter-and-facebook-status-updates/
Integrate your Twitter updates from multiple account and you weblog with your LinkedIn profile. Edit your profile and add applications to include Twitter and BlogLink. Now when you tweet or blog, your LinkedIn profile is updated automatically.
You can also push your tweets to that inactive MySpace account that you still maintain because of the sheer number of users you can reach even though it may not seem like any of your friends are relevant to your target market. But then, maybe that's just me feeling that way. At any rate, this application automatically keeps your account updated with your twitter status: http://www.myspace.com/sync
MySpace also has an RSS application that you can use to post your blog updates but it's not as good looking as the Facebook application.