Things 1.5.4 ↓

Things is task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent filter bar. A Leopard style source list allows for quick and easy focusing. Together with a beautiful user interface, Things aims at the seemingly impossible: making task management both easy and fun.

The big picture. A Leopard style source list lets you easily focus without ever switching view modes or wrapping your head around filter criteria.
A magical tag bar automatically appears when needed and adapts to the currently displayed list. It lets you drill down even the longest list of To-Dos. Hierarchical tags? We got you covered!
Teamwork. Things offers convenient collaboration features. Easily delegate tasks to members of your team. (This is work in progress.)
No columns! Whether it's multiple tags, dates or notes, To-Do items display their information on an as needed basis. No more space wasted by empty or irrelevant column cells!
Out of your head, out of your way. A quick entry HUD lets you enter any idea the moment it hits you. Never let the thought of an unfinished business distract you again.
Yours forever. We won't lock you in. Things will use an open XML file format to store your data. (Not yet activated.)
Things even supports GTD, so if you're familiar and comfortable with GTD concepts, you'll feel right at home.

*Mac OS X 10.6 or later

Version 1.5.4:
Fixed a bug in Things' interaction with iCal Reminders/iCloud causing the generation of blank tasks for some users