Mix any number of RSS feeds into one unique new feed!

RSS Mix: "You can then point a parser at the new feed and display a mix of stories from various sources on your website."

Create an RSS feed for any web page

Page2RSS: "
It is a service that helps you monitor web sites that do not publish feeds. It will check any web page for updates and deliver them to your favorite RSS aggregator."

Can I get site feeds for specific labels?

Blogger: "If a blog you read is using labels and also has site feeds enabled, then you can pick and choose which topics you want to subscribe to. The format for label feeds is this:
http://blogname.blogspot.com/feeds/posts/default/-/labelname"

Ten Technorati Hacks

Micro Persuasion

Polskie kanały RSS

Centrum RSS: "Katalog polskich kanałów RSS"

Top 100 Most-Subscribed-To RSS Feeds

Radio Community Server

Tool to read, parse, merge, and write RSS (and Atom) feeds. GPL

rsstool 1.0.0 has some other functions built-in like text, HTML, or property file output, or templates with custom tags to insert RSS feeds into pages that could be uploaded to a server that supports only static HTML.

The World’s Best Feeds Under One Roof

Feed Vault is actually both a feed directory and a feed reader/aggregator. The great thing with Feed Vault is that aside from letting users browse feeds by topic and add these to their own RSS readers, users can actually read content and content summaries right on the site itself. This is done with the Feed Vault reader feature.