Zoho Invoice - 100% free online invoicing software for small businesses.
Grisbi - Accounting for everyone !
Kamerge - Kamerge simplifies & systemizes the key processes of your business.
Finice - Finice is a sophisticated Money Tracker that aims to bring together all your finances in a single place.
TurboCASH - TurboCASH Accounting Free and Open Source Accounting Software for Small to Medium Business.
Ledger-cli.org - Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line.