Apfp (Arbitrary Precision Floating Point) is a Ruby class for performing arbitrary precision floating point calculations. It also includes a class Apc for calculating with arbitrary precision complex numbers. It also contains a Real class for built-in reals. Both classes keep an estimate of the accumulated error.
APLM (Alex Personal Library Manager) is a set of Perl scripts for managing a small library. It is designed to be easy to set up, easy to use, very customizable, and self-contained. It lets you type in your books, change a few paths, and get going without worrying about MySQL or anything. It also has a Web interface.
APT-RPM is a port of Debian's APT tools for RPM based distributions (Conectiva, Red Hat, SuSE, ALT-Linux, etc). APT is an advanced package management utility front-end which allows you to easily perform package installation, upgrading and removal. Dependencies are automatically handled, so if you try to install a package that needs others to be installed, it will download all needed packages and install them.
ARIA is business class management (ERP) software. It lets you manage inventory levels, maintain payroll, and process orders. It is written primarily in PHP and incorporates the ADODB database abstraction layer. There are currently translations for Chinese, Spanish, Italian, and French.