Microsoft To-Do - Task management tool
DejaGnu - DejaGnu is a framework for testing other programs.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Expect - Expect is a tool for automating interactive applications such as telnet, ftp, passwd, fsck, rlogin...
doo - A smart, simple app for reminders and to-dos
Check - Check is a unit testing framework for C, which runs on environments such as GNU/Linux, GNU/Hurd, BSD, and Mac OSX.