GnuCash - A personal and small-business financial-accounting software, licensed under GNU/GPL and available for Linux, Windows, Mac OS X, BSD, and Solaris.
Ledger-cli.org - Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line.
Rupee - Yet another software engineer.
HomeBank - HomeBank is a free software. Use it to manage your personal accounts. It is designed to easy to use.
YouNeedABudget - Personal home budget software built with Four Simple Rules to help you quickly gain control of your money, get out of debt, and reach your financial goals!
KMyMoney - KMyMoney is a personal finance manager for KDE.