rick has some notes on a Python based RSS Aggregator, which I forget if Joshua was also planning on writing. Good suggestions. A winning app would be those (though maybe not in wxPython) plus:

• Mark Pilgrim's ultra-liberal RSS locator (which sounds like rick's smart search feature, complete with Syndic8 look-up).
• A strict parser for various flavors of RSS, plus Mark Pilgrim's ultra-liberal RSS parser to vocally fall back on.
• Kit's temporal sifting features: show the last N hours, show between XX:YY and ZZ:WW. Also show me all new news since I looked last, which I've been meaning to add to Kit's news page.
• Kit's searching features: show me the current news about "dmca."
• Grouping like Kit should have, along with group export and import.
• Some notion of read and unread items, as mentioned in the linked item above and as one of Kit's temporal sifting features.
• Periodical scan as an option; lots of people like the idea of Aggie's no regular scan and a "Scan Now" button.
• Irregular periodical scan. If I wait an hour to scan feed J again, but there are no new items, wait two hours next time. This could be as complicated as reading a feed only if there's a better-than-not chance the feed updated this particular hour of this particular day of the week.
• P2P feed sharing. This is kind of out there, but I'd like to be able to help distribute feed X, especially if it's popular. Lot of P2P work applies, so discussion of this would be good for the aggregators group where there are, like, smart people and stuff.