I’ve slowly built exactly this as one of my side projects over the last few years. An OSX menu bar app that uses a combination of ofxclient and reverse engineered APIs to download balance/transaction info directly to an Excel spreadsheet. This way I get to leverage Excel as my UI for categorization, analysis, graphing, etc.

I’ve been debating for a while what to do with the app next but didn’t think many people would be interested. Is this the the kind of thing you’re looking for?