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In case you’ve been living in a box, the three most compelling options in the world of Mac task managers are: Things (if you like a simple, beautiful interface), OmniFocus (if you need lots of powerful features), and TaskPaper. TaskPaper eschews the standard feature bloat of GTD applications and provides instead the minimum tools you need to manage your tasks easily and effectively. TaskPaper task lists are plain text (so you can take and edit them just about anywhere) but enhanced with features like automatic formatting, archival of completed tasks, and easy filtering/searching of your task list. TaskPaper 2.0 adds a fantastic new search system (watch the screencast), a Things-style quick entry window to add tasks from anywhere on your computer, drag and drop organizing, a customizable theme system, Applescript support, and an even more attractive user interface.

I strongly recommend TaskPaper even to people who think their needs are met by more complicated software. There is nothing like using a minimalist tool like TaskPaper for a couple of weeks to learn exactly what features you can live without and which you desperately need in a task manager, and for many people TaskPaper will be the solution that finally gets out of their way and lets them complete their tasks rather than fiddling with them. TaskPaper 2.0 is a free upgrade to users of TaskPaper 1 (although it now requires OS 10.5), or is available for $29.95 with a free trial.