PracticePanther - PracticePanther offers CRM, invoicing, time tracking and communication solutions for law firms.

EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.

Clio - Clio provides a full suite of web-based practice management tools targeted specifically at the administrative needs of sole practitioners and small firms.

Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

MyCase - Practice More, Manage Less.

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.