Thinking about RSS today so I guess it's time for a post to @simon's #projects community:
20yrs ago I wanted a simple way syndicate event information between protest.net, Indymedia.org, and other activist sites. MagpieRSS is what came from that. It differed from other RSS parsers at the time by being written in PHP, and having built in caching vs just being a parser.
For a while it powered RSS parsing for Wordpress, and Slack, and many of other projects.