Acuity was developed by AlkSoft to allow those Macs running the classic Mac OS to have access to RSS feeds. There's nothing wrong with the classic Mac OS, and RSS certainly doesn't require a fancy new Mac to work. RSS feeds can now even be read on a 68k Mac.
Acuity allows the contents of a feed to be browsed as a list of headlines. Click on a headline to view that story's summary as prepared by the publisher. Feeds can be automatically updated every so many minutes, and a feed can be subscribed to in a fashion similar to bookmarks in your favorite Web browser.