TuDu is a comand line interface to manage hierarchical todos. Each task has a title, a long text description, a deadline (tudu warns you when the date is close), and a scheduled date. There are categories and priorities.
A screenshot: 
The source can be downloaded from: tudu-0.6.1.tar.gz
Older versions:
Packages:
The development is done on a git repository on gitorious: git://gitorious.org/tudu/tudu.git
Ruben Pollan (meskio) meskio@sindominio.net