ITWALES.COM - How do Open Source groupware solutions measure up?
An open source package (runs as a console application) that is intended to be reminiscent of Lotus Agenda
Lotus Agenda Excite search for +Lotus +Agenda
In the "Windows" world, a fairly unique PIM system is Ecco. It appears to have the model that events go together to define "projects," and thus is fairly useful for people involved in project management.
It knows how to sync data with 3Com PalmPilots and possibly other PDAs; Ecco has been discontinued.
Informant is a set of utilities for keeping a user informed of events. It consists of an informant, which is the means by which the user is alerted to the occurrence of the said event, and a number of sources that "whisper" an alert to the informant when the event occurs.
Dasher is an information-efficient text-entry interface, driven by natural continuous pointing gestures.