Below are some free and open source accounting packages...
Adempiere — ERP Business Suite
Compiere — ERP solution automates accounting, supply chain, inventory and sales orders
ERP5 — Python and Zope based ERP
FriFinans — OpenSource finance application (offers, orders, invoices, products and more).
GnuCash — Double-entry book-keeping
Grisbi — Single-entry
HomeBank — for personal use
JGnash — Java-based, double-entry book-keeping
JQuantLib — Java-based Quantitative Finance API framework for financial instrument valuation and more...
JStock — Java-based, stock market software which supports multiple countries
KMyMoney — Double-entry book-keeping
Marketcetera — trading platform
Mifos — Microfinance Institution management software
n21 eBusiness Suite — web based ERP / CRM
OpenERP — ERP system
OpenXpert/Xpert — Fund accounting on Linux and Windows 98/XP
QuickFIX/J — FIX protocol engine written in Java
SQL Ledger — Double-entry book-keeping
TurboCASH — Double-entry book-keeping for Windows
more info is available at List of free and open source software packages - Wikipedia, the free encyclopedia
20th October 2009 From India , Bangalore