PIM Xtreme is a free Open Source application for management of personal information (PIM: Personal Information Manager) configurable and highly flexible (or at least that is the goal). It aims to be a powerful organizer for your personal data.
You can handle information such as Contacts, Notes, Tasks (to-do), Events/Appointments, Calendar, Financial Accounts & Movements, Alerts, and many other useful features.
All this information is stored in a relational database (MySQL for the moment) to be able to be accessed and consulted in a flexible way. It also allows exporting most of its data to several standard formats (CSV, XML, iCalendar, etc.).