1. Asana – a web app, also available on iOS and Android, that lets you assign tasks, set priorities and deadlines, and monitor task and project statuses.

2. Trello – a popular online service that lets you organize your tasks, to-do lists, discussions, and ideas on a single board.

3. Slack – a web service (also available for desktop, iOS, and Android) for creating chats and groups for discussions with your team, clients, or users.

4. GanttPro – a Gantt chart app that lets you plan and manage projects online, visualize processes, create tasks and assign them to participants, set deadlines and completion percentages for individual tasks and the project as a whole, add milestones, and share your Gantt chart with your team and clients, allowing them to view or edit it.

5. Basecamp – One of the most popular online services for project collaboration, it allows you to share documents, conduct team discussions, create to-do lists, add comments to tasks, and send and receive emails.

6. Merlin – Another Gantt chart software for Mac OS X with the ability to track project expenses and budgets.

7. Wrike – A unified system for working on projects with your team, offering advanced functionality: it allows you to assign roles and create a workspace for each department, set and discuss tasks, track their status and progress, share files, display project tasks on a Gantt chart, and receive weekly reports.

8. ProofHQ – An application that allows you to share documents/designs/prototypes, comment with your team, and make decisions together, allow clients to leave comments, and download and share different versions of a project.

9. SprintGround – an Agile/Scrum service for task management, sprint and release planning, progress tracking, and team collaboration. It allows for bug reporting and feature requests based on user feedback.

10. MS Project – a giant in the project management market, based on the Gantt chart, allows for project planning and resource management, what-if scenario planning, and setting and monitoring deadlines and progress.

11. Kanbanery – a popular service for project management using a Kanban board.