Mac OS X only: New task manager Things, now in alpha testing, is a promising new option for Mac users looking to get organised on the desktop. Structurally, Things categorises tasks in a very Getting THINGS Done way (get it?), with an inbox, projects, and "next" (or Next Actions) view, as well as support for contacts to whom you may delegate tasks and tags (which you can use for context.) After the jump, check out some screenshots of the alpha version of Things.
Each of your "Things" is actually a task, to which you can assign tags, a due date, and notes. File a task in any area listed on the sidebar: Today, Next actions, the Inbox, a project, an area of responsibility or to any contact.
Quickly get stuff off your mind and into Things using the Quick Entry form.
File multiple actions under a given project, which can also get a due date and tags.
Switch between views in Things on the sidebar. As you select various views or tasks inside Things, the applicable tags get displayed on the top bar. You can drag and drop any task to an area in the sidebar; search from the built-in entry box on the bottom right of the window, and when you mark tasks as complete they show up in the Logbook, where you can see everything you've gotten done. The part I really like about Things is that it doesn't lock up your data in an unrecognisable format: a plain text XML file can be read by any other app that understands it.
At first blush Things is convincingly slicker and sleeker than iGTD. The alpha version is still very early, and it's a free download for Mac when you opt in to test it on their front page. The final release, however, will not be free.