You may be shocked to learn that not all feed reading and feed producing software adheres strictly to the RSS and Atom specifications, nor to the recommended practices for the use of them. Yeah, right. I doubt that comes as a surprise to any of you. Perhaps the best way to convince software vendors to get their act together would be to build a Newsfeed Software List of Glory and Shame. It would be divided into approprate categories for easy perusal and comparison (Mac feed readers, Windows blogging tools, etc.), with a checklist of important features for each. For example, if a feed reader properly uses If-Modified-Since and/or ETag headers when it loads feeds, it gets a glory mark. If it doesn't, it gets a shame mark. The software in each category is listed in order of how many glory marks each gets so that those perusing the list can find the best-behaved software easily.

I would not advocate making such a list until I finish the next version of CaRP ;-). At the moment, it doesn't use If-Modified-Since or ETag. At least it defaults to polling no more than once per hour.