WordPress generates a number of other feeds in addition to those for posts and comments. There’s a feed for each of your categories and tags. You can also get feeds of posts written by an individual author. You can even get feeds for search results!
Since WordPress doesn’t advertise these hidden feeds, you’ll have to do a little URL manipulation to find them. Of course, once you’ve located them, you can place the links somewhere in your theme so your visitors can find them too.
Since RSS 2.0 and Atom 1.0 are the most popular formats, I’ve given those as the examples for the hidden feeds. However, all four formats are available for all the feeds listed below (except Links). If you want RSS 0.92 or RDF feeds, just replace the appropriate acronyms in the URLs.
Are there any more that I’ve overlooked? Let me know!