1. GnuCash
GnuCash is a personal and small-business finance manager with a check-book like register GUI to enter and track bank accounts, stocks, income and expenses. GnuCash is designed to be simple and easy to use but still based on formal accounting principles.
2. Money Manager Ex
Money Manager Ex is an easy to use, money management application. It is a personal finance manager. It can be used to track your net worth, income vs expenses etc. It runs on Windows, Linux and Mac OSX.
3. A Java library for reading/writing Excel
JExcelApi is a java library which provides the ability to read, write, and modify Microsoft Excel spreadsheets. This project mirrors the files on jexcelapi.org, which has been known to go down on occasion.
4. Buddi
Buddi is a simple budgeting program targeted for users with little or no financial background. It allows users to set up accounts and categories, record transactions, check spending habits, etc.
5. KMyMoney
KMyMoney is the Personal Finance Manager for KDE. It operates similar to Quicken, supports various account types, categorization of expenses, multiple currencies, online banking support via QIF, OFX and HBCI, budgeting and a rich set of reports.
