Out of the box, WordPress generates a number of RSS feeds for you automatically. These include feeds for comments, posts, and believe it or not, categories. I had previously thought that a plugin was required in order to turn categories into RSS feeds but that is not the case. Check this out.
WordPress supports a number of different syndication specifications, those of which are listed below along side their respected WordPress generated URL.
RSS Spec / WordPress URL
RSS 0.92 / http://www.yourdomain.com/wp-rss.php or http://www.yourdomain.com/?feed-rss
RDF RSS 1.0 / http://www.yourdomain.com/wp-rss2.php or http://www.yourdomain.com?feed=rdf
RSS 2.0 / http://www.yourdomain.com/wp-rss2.php or http://www.yourdomain.com/?feed=rss2
Atom Feed / http://www.yourdomain.com/wp-atom.php or http://www.yourdomain.com/?feed=atom
Comments RSS Feed / http://yourdomain.com/?feed=rss&p=50 where p stands for post and 50 is the post id.
Now here is the feed link which I found interesting.
Category RSS Feed / http://www.yourdomain.com/wp-rss2.php?cat=50 where cat stands for category and 50 is the category ID.
Finding the ID number for a category is easy if the blog your browsing is not using pretty permalinks. However, if the blog IS using permalinks, you can type in the following URLs to access their RSS Subscription Links.
http://www.domain.com/feed – Main RSS Feed
http://www.domain.com/comments/feed – Comments RSS Feed
http://www.domain.com/category/category-name/feed – RSS Feed For That Category
Why would you want to know this information? Now, if you come across a site that publishes articles within only a category or two of interest, you can subscribe directly to those categories instead of the entire blog making your RSS reader that much more efficient. For instance, I occasionally publish jokes or perhaps something out of my personal life when all you really care about, are reviews or news.
Thoughts and Insanity From Jeff 
Generally, if a site uses “clean urls”, you can add /feed to the end of any url (whether its a post, main page, category, etc), and it’ll subscribe you to that feed. If they aren’t using clean urls, then as you show with wp-rss.php, etc, they’d have to do that…
<3 Clean URLs.
@Chris Thomson Right on Chris. The last three URL’s I provide are for those who use Clean URL’s. I never knew about this in WordPress so I thought I would share after I discovered it.
I almost installed a plugin to turn my categories into RSS feeds but it looks like thats done automatically.
What happens if I turn all the categories into tags? Do I then have an RSS feed for every tag on my blog?
I just tested this with a local install of WordPress, and yes, you can make feeds out of tags, however, I’ve noticed you use the Feedsmith plugin (me too!), which will redirect that feed to your main feed, although, if you had the feedsmith plugin disabled, it should work fine by adding /feed to the end of something like jeffro2pt0.com/tag/wp. :)
Some time ago I was wondering why that thing doesn’t work properly. Good to know I can blame Feedsmith plugin…
<3 Clean URLs too, especially those with .html suffix :P