CiviCRM - A Constituent relationship management for the Civic Sector
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
EspoCRM - EspoCRM is open source CRM (Customer Relationship Management) software that allows you to see, enter and evaluate all your company relationships regardless of the type.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Pipeliner CRM - Pipeliner CRM empowers small to medium-sized sales teams to close more deals and lower risk. Implementation and training are a breeze. Mac & Windows.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.