GnuCash - A personal and small-business financial-accounting software, licensed under GNU/GPL and available for Linux, Windows, Mac OS X, BSD, and Solaris.
Clio - Clio provides a full suite of web-based practice management tools targeted specifically at the administrative needs of sole practitioners and small firms.
Synder - AR Automation
MyCase - Practice More, Manage Less.
Xero - Xero is online accounting for your small business.
PracticePanther - PracticePanther offers CRM, invoicing, time tracking and communication solutions for law firms.