A discussion in my QuickPHP forum has resulted in this new idea where PHP Script can simply be used to create a plugin. Rather than the conventional DLL plugins, we simply get the host to call into the PHP script and get the results back from it.
Of course, a DLL plugin has its advantages (i.e. compiled and runs faster), but in cases that require you to allow your user to configure part of your software with great flexibility, instead of using INI / XML files, a PHP file is definitely not a bad idea. That would bridge the chasm between a DLL plugin and a simple config file. What's more - you only need to deploy the php DLL file (e.g. php5ts.dll) along your software and that's it! You get PHP's powerful regular expression out of the box!
In the discussion, I suggested that PHP could be used to implement the entire Apache's mod_rewrite module, without the need for an external INI file with an input and output regular expression. Users would simply need to write PHP script to manipulate the client request info and return it back to the server. This also means that QuickPHP's mod_rewrite functionality could be so much more powerful than Apache's. In fact, I think one main PHP file is all I need - the main file, in turn could simply call into other modules to work its magic if it's required. If QuickPHP_ReqMod.php is not found, QuickPHP reverts back to its basic mode. No additional DLLs - no unnecessary memory usage.