Fever was an RSS reader developed by shaun inman. My interest in it stems from the fact I found an archive and briefly used it as my main RSS reader.

My experience with it was generally pleasant, though I spotted some downsides immediately. This could be down to the fact that I just didn’t use it the way it was intended…I mean, I don’t exactly read a lot of blogs…but the actual fever feature I mostly ignored.
Oh yeah…the fever feature is basically a means of tracking recent trends. It did this by finding links that were shared among your feeds and then displaying them with a temperature ranking based on how frequent they were. I’m realizing right now, as I write this (2025-05-26) that this could actually be somewhat useful in combination with Hatena.
To summarize my thoughts…I think the concept behind it was good, but the execution was a bit iffy. It was also a bit resource-hungry as far as I remember…and had trouble with hundreds of feeds even though that was the entire point.
Fever mostly survives via its API, which continues to be supported for syncing.