I've been recently experimenting with a few auto-blogging Plugins for Wordpress. Well... Its NOT for creating a splog, or earning those Adsense pennies. The intention was to compile well-written Sanskrit articles published across the web, and create a Digest. I decided to use Wordpress for greater flexibility and support. Following are the plugins I found that helped me create the auto-publishing Digest.

ReBlog
A reBlog facilitates the process of filtering and republishing relevant content from many RSS feeds. reBloggers subscribe to their favorite feeds, preview the content, and select their favorite posts. These posts are automatically published through their favorite blogging software.

Feed2Post
This allow the automatic creation of new post based on external feeds content

Wp-O-Matic
This makes autoblogging a snap by automatically creating posts from the RSS/Atom feeds you choose, which are organized into campaigns.

FeedWordPress
This is an Atom/RSS aggregator for the WordPress weblog software.

For tips on how to use wp-o-matic plugin, check out Blogging Empire. It has a few guidelines on how to use the plugin ethically, and provides a few resources that you can make use of.