Ideally, this stuff will all have an API that I can build on top of. Do such tools exist?
Also, is there a bank or credit union with an awesome API?
What's nice about spreadsheet software is that you can do whatever you want, there's no fixed way to track expenses or plan/budget. But that can also be a downside, as I've rewritten parts of it numerous times when I found out I forgot to take certain things into account (no pun intended).
It appears Yodlee may be something you'd be interested in.