GnuCash Double-Entry Accounting Program.

You Need a Budget combines easy software with Four Simple Rules to help you quickly gain control of your money.

KMyMoney strives to be the easiest open source personal finance manager to use, especially for the non-technical user.

Mint.com is a free, web-based personal financial management service.

HomeBank is a personal accounting software package that runs on OpenBSD, Linux, FreeBSD, Microsoft Windows, Mac OS (via macports or homebrew) and AmigaOS.