This is the best free RSS to Twitter service. It lets you create automatic rules around which posts you want to send to Twitter, add automatic hashtags to tweets based on category and author of posts, and much more. You can even use it to automatically post RSS to Facebook and Myspace.
Dlvr.It is completely free, and you can configure multiple RSS feeds with it. This comes especially handy if you manage multiple websites. This will let you choose which RSS feed should go to which Twitter account.
Check out Dlvr.it free here.
NetworkedBlogs is a Facebook application that lets you publish blog feed to Facebook. This is what I am also using to publish RSS feed of this blog to my Facebook Fan page. You just need to add RSS feed of your blog to this application, and authorize it to publish updates on your Facebook fan page. This application will then publish your RSS feed to Facebook. It is quite easy to use, easy to setup, and works well.
Most of the people know Twitterfeed as RSS to Twitter application. However, it actually lets you post RSS to Facebook as well. Twitterfeed comes with flexibility that you can add multiple RSS feeds, and multiple social networks, and closely control which feeds get published on which social network. I use it for publishing my RSS feed to Twitter (I am not using it for RSS to Facebook, as I didn’t know earlier that it lets you publish blog feeds to Facebook0ok).
Ping.fm also lets you publish RSS feed Facebook, apart from many other social networks. Main feature of Ping.fm is that it lets you post to over 30 social networks, including, Twitter, Facebook, LinkedIn, and more. You can add your RSS feed to Ping.fm, and it will check new items in that, and post to your social networks, including Facebook. This is also completely online, and free.
RSS Graffiti is another Facebook application like NetworkedBlogs that lets you post RSS feeds on Facebook. It is quite feature rich, and lets you post any number of feeds to any Facebook pages. You just need to add this app to your Facebook profile, give it authorization to post on your profile, and then add the RSS feeds that you want it to monitor. It will regularly check those feeds, and post new items to your Facebook page.
All these free RSS to Facebook applications make it extremely easy to keep your Facebook profile updated with your blog feed. If you know of some other application that we might have missed, mention in comments.