Instant RSS Search is a Google powered feed engine to help you discover RSS feeds around your favorite topics. Try one of these sample search queries:

tech news - find RSS feeds of all the popular blogs and news websites that cover technology related topics.
site:thenextweb.com - find all the RSS feeds offered by your favorite web publisher (like thenextweb.com).
edward snowden site:nytimes.com - find all RSS feeds around a particular topic from a single website (like The New York Times).
allintitle:revision3 - find podcasts feeds from Revision3.
google inurl:twitter.com - find all the official Google accounts on Twitter.

rss of twitter user feeds by screenscraping with perl

Free online RSS generator.
Create RSS from any web page. Build RSS feed for your site or generate XML for personal usage

Create RSS feed for any webpage or podcast. Extract data and turn dynamic websites into spreadsheet or API.
Feedity is an online RSS feed generator and podcast feed builder tool.