Billing - Cash register, payroll and HR software are available here, as well as applications to assist in the invoicing of customers and providing quotations.
Miscellaneous - Software that doesn't quite fit into any of the other categories. Includes libraries for online banking, auditing software to help detect fraud, simple calculation software, a free alternative to MIPS/VersaCheck, tools to print cheques and more.
Personal Finance - The highlight of this section is GnuCash, which allows you to track bank accounts, stocks, income and expenses. As quick and intuitive to use as a checkbook register, it is based on professional accounting principles to ensure balanced books and accurate reports.
Stockmarket - A good selection is available including stock portfolio performance monitoring tools, software to calculate the value of a call using the Black and Scholes method, the Value At Risk (VAR) of large credit portfolios using the Monte Carlo method, access to time-delayed stockquotes from a number of sources, ticker applications, and more.
Taxes - As Daniel Defoe said in 1726, "Things as certain as death and taxes, can be more firmly believed". Although few of us enjoy paying taxes, this section could help you to prepare your tax forms, and may even help to determine if you are entitled to a refund!