php-msrpc is a PHP binding for MSRPC, which is Microsoft's proprietary protocol for managing Windows servers and the like. It uses the libraries provided by the Samba-TNG project, which is required for use. php-msrpc will enable you to write Web-based administration tools for Windows (such as a user manager) with a Web server running under Linux.
SAPRFC is the extension module for PHP that allows you to call ABAP functions in an SAP R/3 system from PHP scripts. It is also possible to write an RFC server program in PHP, and call PHP functions from ABAP. Other features include using the RFC (Remote Function Call) API to make a call, discovering the interface of a function module, and mapping all RFC types to PHP strings (delivered with a test script that has a similar function to the "Single Test" option in the SE37 transaction).
APD is a general purpose non-interactive PHP profiler/debugger that produces formatted strace/truss type reports. APD supports full stack backtraces via calls similar to croak() in Perl's carp. APD is a Zend Extension and is designed to provide timing with the minimal performance impact. APD supports varying levels of debugging and can be turned on/off in individual scripts.
PHP-Authentication works like the Tomcat authentication. You give the source to authenticate against (DB, file, XML-RPC, etc.) and the directories that shall be protected, and the class handles the rest. No including of any call to a class method on every page is necessary. You can also use it as if it were a standard Auth-class, using a call to "isLoggedIn" on every page that shall be protected.