GMoney downloads your bank account transactions and inserts them into a Google spreadsheet. You can write additional sheets to generate summaries, spending reports and charts. (I have a pretty complex spreadsheet with spending reports and graphs but I don't know a good way to make that general and shareable, ideas are welcome.)
Unless you use one of the banks that I've already written an interface for, you'll need to roll up your sleeves and write a few lines of code to script logging in to your bank and clicking the "download transactions" link. But it's not that hard, it's done using the awesome mechanize library. See accounts/pc_financial.rb for an example. If you do that please send me a patch or pull request and I'll add your bank.
Your account details (login, account id, password, etc) go into $HOME/.gmoney/config.rb
This is free software, and you are welcome to redistribute it under certain conditions. This software comes with ABSOLUTELY NO WARRANTY. See the file named COPYING for details.