Teamwork.com

Task & Milestone Management* Assign tasks to one or more people* Create recurring, dependent and sub-tasks* Attach files to tasks* Associate tasklists with Milestones* View/Edit project Gantt Chart* Create tasks via emailFiles & Messages* Centralize communication using Messages* Attach files to messages* Reply-by-email functionality on Messages and Comments* Upload and share project files* Integrates with Google Drive, Dropbox & Box.comTime Tracking & Invoicing* Track time on projects or tasks* Add estimated time to tasks* Run time reports for all users* Export invoices to Freshbooks, Harvest, Quickbooks Online, Xero and many more services* Mac/Windows Timer App availableNotebooks & Google Drive* Create notebooks to share project information* Integrates with Google Drive for realtime document collaboration with colleaguesMobile Support* Native Mobile Apps available for iPhone, iPad and Android* HTML5 mobile version for access on the goPrivacy & Notifications* Make all items available to specific users and companies* Add people to multiple projects* Receive and reply-to email notifications* Daily Report, iCal and RSS feedsMake it your own* Custom themes and branding* Custom Domains available* Google Apps users can sign in with one click* Full REST API