http://sourceforge.net/projects/turck-mmcache/
Turck MMCache is a PHP Accelerator & Encoder. It increases performance of PHP scripts by caching them in compiled state, so that the overhead of compiling is almost completely eliminated. Also it uses some optimizations for speed up of scripts execution.
Win & Linux. Binaries from 2003. Seems not to support PHP Version > 4.3 :(
Quelle1)
The PHP language was originally implemented using a PHP interpreter. Several compilers now exist, which decouple the PHP language from the interpreter:
Advantages of compilation include not only better execution speed, but also obfuscation, static analysis, and improved interoperability with code written in other languages.
(Commercial)
The #1 http://shop.zend.com/de/zend-guard.html (600$/Year)
(Commercial)
http://www.intricks.com/projects/PhpCodeBuster
PhpCodeBuster, a freely available and open source PHP class to protect your PHP code. Using PhpCodeBuster, your PHP scripts will get obfuscated, meaning that the code is changed in such a way that it is very hard te reverse engineer it into a understandable format.