Syndic8 is a project to gather as many syndication feeds as possible together. You can browse the categories or search through the feeds, and each one has a link to the actual, original feed. Also, they have an RSS file available with all of the feeds listed in it, so it would be possible to make a script to import all of them into Scoop, though that probably isn't the best idea, considering the file is 1.5M and has over 7500 URLs listed in it.

I might have to try importing it, though, just to see if Scoop can scale up that far :) Of course, even if it could, the amount of time it would take to look through them and choose the ones you want to enable would be insane.