Magot is a cross-platform personal finance manager written in Python. A check-book like register GUI allows you to enter transactions and track bank accounts, incomes and expenses. It's based on formal accounting principles, PEAK and WxPython.
Account Guard helps you monitoring your expenses. Spend a few minutes every other day with an easy to use GUI and it will tell you where you can improve on your financial situation. Core is a simple but complete library for single-user data-applications.