Blogs is great way of discovering and learning specific subjects:)
As for me the most interesting posts in blogs is with code snippets,
news
and use cases.
I prefer:
http://feeds.feedburner.com/RidingRails
http://feeds.feedburner.com/LoudThinking
http://www.onrails.org/xml/rss20/feed.xml
http://railsexpress.de/blog/xml/rss20/category/rails-plugins/feed.xml
http://feeds.feedburner.com/RubyInside/
And local russian-language blogs.
What rails blogs do you read?