I want task management tool that integrates seamlessly with my development IDE, as I am using Eclipse WTP mainly, I researched Eclipse plugins and found Mylyn.
I created local repository of tasks and simply starts, and mark task completed. Mylyn takes care of calculatig the time spent on each task. When I finish tasks and commit chnges to subversion, Mylyn automatically list tasks in my commit note dialog box.
However, Mylyn have wider scope of what I am using, see the following Mylyn description from its web site: http://www.eclipse.org/mylyn/
Mylyn is a task-focused interface for Eclipse that reduces information overload and makes multi-tasking easy. It does this by making tasks a first class part of Eclipse, and integrating rich and offline editing for repositories such as Bugzilla, Trac, and JIRA. Once your tasks are integrated, Mylyn monitors your work activity to identify information relevant to the task-at-hand, and uses this task context to focus the Eclipse UI on the interesting information, hide the uninteresting, and automatically find what’s related. This puts the information you need to get work done at your fingertips and improves productivity by reducing searching, scrolling, and navigation. By making task context explicit Mylyn also facilitates multitasking, planning, reusing past efforts, and sharing expertise.
If you want richer features of Mylyn, try its commercial version TaskTop at: http://tasktop.com/tasktop-for-eclipse/