PracticePanther - PracticePanther offers CRM, invoicing, time tracking and communication solutions for law firms.
GnuCash - A personal and small-business financial-accounting software, licensed under GNU/GPL and available for Linux, Windows, Mac OS X, BSD, and Solaris.
PHC FX - PHC FX is a comprehensive solution that offers a wide range of functionality at any price.
Synder - AR Automation
iDempiere - iDempiere Business Suite ERP/CRM/SCM done the community way.
Xero - Xero is online accounting for your small business.