Mark Liyanage has released an excellent PHP 5 installer for OS X. Libraries included with the installer are:
* the MySQL and PostgreSQL databases
* the PDFLib PDF library
* the cURL library for various communications protocols
* the GD image creation library (with PNG, JPEG, PostScript Type 1 and TrueType font options).
* the expat XML parser and WDDX support
* XSLT transformations
* LDAP access
* the IMAP client library
* FTP client access
* exif digital camera image metadata support
* transparent session id propagation (--enable-trans-sid) option
* mcrypt encryption functions
* sockets extension (experimental!)
* iODBC database support
* XML-RPC support (back in after I had to remove it in a previous release)
* mhash support
* GNU gettext
* XML-DOM
* PEAR
* CLI Version
There’s not much more you’re going to need unless you’re using some obscure libraries.