Simsttab (which stands for "Simplistic School Time-Tabler") is a timetabling engine that can generate timetables satisfying requirements typical for secondary schools in Austria ("Gymnasium"-type), Germany, and maybe other European countries. It supports coupling of lessons and rudimentary room reservation.
Nomad PIM is an extensible personal information manager. It allows you to keep track of your personal data and provides modules for notes, schedule, contacts, money, diary, and timetracking. It is implemented as an Eclipse RCP application. Like Eclipse, it provides extension points for extensions by additional plugins.