Interactive Pie Charts and Detailed Breakdown Pages
The pie chart model view is currently shows the expenses by category, and displays all eligible expense categories.
It would be a useful and intuitive feature to be able to click on a slice, and get more details on that category. Perhaps, that would lead to another pie chart that is generated from the expenses in only that category and subcategories.
What I would like to see is a page dedicated to detailing expenses. Such a page would show the expense pie chart, plus a listing of all the expenses that was used to generate it. Ideally, the list could also be sorted.
Combined with the interactive pie chart, you would be able to navigate to these pages by clicking on the slice you want detailed. (Navigating these pages could also be included in the existing side bar, or whatever would make sense.)
Ultimately, I would like a system that allows users to easily narrow in and zoom out on expenses, while providing detailed breakdown information.