EssentialPIM is recommended for individuals, freelancers, and small businesses seeking a centralized and efficient tool for managing various types of information. It is especially beneficial for those who prefer an all-in-one application to keep track of meetings, tasks, contacts, and emails without needing multiple separate apps.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
Buku - A powerful command-line bookmark manager.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
GTDNext - About Us.