Dear Professor Lazyweb,
Let's say that, for some stupid reason, I'm thinking of implementing Yet Another Blog-Aggregator-Type Thingy that I want to work with most blogs and syndication feeds that exist today. Which formats do I need to support? RSS 0.91? RSS 1.0? RSS 2.0? Atom? Others?
(I know I probably also want to support OPML for importing a list of feeds as well.)