WordPress generates RSS feeds for just about anything. Typically you can find the RSS feed for a site at:

http://thesitename/feed  or http://thesitename/feed/rss2

You can get a feed for all the comments at:

http://thesitename/comments/feed

or comments for a specific post at:

http://thesitename/post-name/feed

or a feed for new blog posts for a specific category at:

http://thesitename/category/categoryname/feed

or for a specific tag at:

http://thesitename/tag/tagname/feed

The WordPress feed program is actually surprisingly flexible. You can read the complete documentation at WordPress Codex.