I've been working a personal finance web app focused on measuring and improving spending behavior. It goes beyond merely "how much did you spend" and addresses the context and decision making process which drives good or bad spending.

The big challenge has been keeping it simple yet providing the appropriate prompts for folks to reflect on and improve their spending decisions. In other words, the code is easy; the product design has been harder for me.

Teaser: http://www.spendlight.com/

With luck I'll bring the first batch into the beta in the next few days. Invite code "HN" will bump you to the front of the line.

How are you handling the actual accessing of user's finance data? Automatically via API? Or having them maintain a ledger?

For now it's manual input. A lot of folks balk at this, but I find I do better when I'm forced to thoughtfully engage with my budget.

For example, my wife and I are primarily concerned about improving our grocery spending. This means that we only have to input spending 2 or 3 times each week. It's really not a burden, and really helps keep our use of the app simple. All of the other spending that goes through our checking account isn't mixed together. It allows us to be very focused.

I sometimes think of it in the same vein as workout/fitness apps. Manually recording some aspects of your activity shouldn't kill the deal. And in our case, we encourage you to do self-evaluation... and that wouldn't come through a feed from your bank anyhow.