Free Invoicing Software - Free Invoicing Software provides the facility of online billing.
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
Ledger-cli.org - Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line.
Invoice Ninja - Invoice Ninja is a free, open-source solution for invoicing and billing customers.
Hyperlogs - Are you still using spreadsheets to keep track of time? Time Tracking has never been this easy.