Osmo is a handy personal organizer, which includes calendar, tasks
manager and address book modules. It was designed to be a small, easy
to use and good looking PIM tool to help managing personal information.
In its current state the organizer is quite convenient to use - for
example, the user can perform nearly all operations using the keyboard.
Also, a lot of parameters are configurable to meet the user's
preferences. On the technical side, Osmo is GTK+ based tool which uses
a plain XML database to store all personal data.
from Pierre-Emmanuel Andre <pea at raveland dot org> with some tweaks