OmniFocus!

Todoist is a task manager thats useful, fast and easy to use.

Asana is a web and mobile collaborative work management app that goes beyond typical collaboration software by enabling teams to track everything they're working on. With tasks, projects, conversations, and dashboards, Asana lets your team know who's doing what by when to help you get results. Use Asana for team communication, setting meeting agendas, running brainstorms, sharing files, or creating shared calendars--anything you can think of. You can also add partner integrations to customize Asana for your team with functionality like Gantt charts, time-tracking, and Google calendar sync. Asana is available on web, iOS, and Android and is free for teams of up to 15 people. »

Workflowy lets you organise your brain into easily manageable lists. It also works as a single-pane outliner with inline notes. It offers one-click hoisting (zooming into branches). The online version syncs with mobile apps.

Take your tasks anywhere with this feature-packed application.

An easy to use, web-based to-do list. Get organized, stay motivated, and be more productive.

Any.DO helps you get things done with your friends in a simple & elegant way. It's free, simple & fun.

Opensource task & productivity management tool for startups, engineered based on the concepts of OKR.

Quire is a new-generation collaborative task management tool for organizing tasks in a tree-like structure wrapped in simple and user-friendly UI.

From a simple checklist to full-blown project management, 2Do is an incredibly powerful, award winning, task manager that lets you focus on what's important.

Make lists and get organized. TaskPaper is a plain text to-do list that’s surprisingly adept.

Taskwarrior is an ambitious project bringing sophisticated capabilities to a simple and elegant productivity tool. You'll find it has customizable reports, charts, GTD features, Lua extensions, device synching and more, all while our international team provides excellent support!

Moo.do is designed to be the best and easiest way to keep your life and thoughts organized: projects, to-do lists, appointments, contacts, reminders, events, and anything else you want to write down. As all modern apps should be, Moo.do is available on any computer, tablet, or phone and synchronizes all devices and users in realtime.

Simple GTD application to manage your tasks and to-dos. Syncs with web server. Complete with the usual Inbox, Today, Next, Tomorrow, Scheduled and Someday "buckets" as most GTD programs have. You can also create Projects for tasks with multiple steps.