GnuCash - A personal and small-business financial-accounting software, licensed under GNU/GPL and available for Linux, Windows, Mac OS X, BSD, and Solaris.
Teamleader - CRM, invoicing & project planning in a single tool for SME's
Fentury - Personal financial advisor, money & budget manager
Free Invoicing Software - Free Invoicing Software provides the facility of online billing.
HomeBank - Access Financial Services. Easy, fee-free banking for entrepreneurs Get the financial tools and insights to start, build, and grow your business.
Invoice Ninja - Invoice Ninja is a free, open-source solution for invoicing and billing customers.