As I just updated the "Syndicate!" with the address of a new RSS Validator I noticed that the parent URL of this tool looks promising: http://feeds.archive.org/
At the moment the only answer from the server is:
Coming soon...
These aren't the droids you're looking for...
Projecting the nature of http://archive.org/ onto news feeds I think whatever may be planned there could be very interesting. Imagine a way back machine for news feeds, with the functionality of http://syndic8.com/ but with an infinite memory! You would be able to scan through every single headline of every present and past blog. Scary, but very interesting!
This is just an assumption, but what else should be planned under within that domain?