You can see if there's a feed referenced in the page you're on by simply doing `curl |egrep rss\|xml` or just show source.
The best experience I've had is using a browser extension that detects the tag, shows an icon, and lets me use it to subscribe with a custom /subscribe?url= link; but the extension I was using kept crashing on presumably non-spec feeds.
Bonus would be if someone came up with a protocol for your feed reader to advertise to the extension that it can handle subscribing to feeds to simplify configuring a custom reader.
Can anyone recommend an extension for FF?