Pharen is compiler project that compiles a Lisp-inspired language to PHP.
It is still under development, but small-scale use is definitely possible.
All documentation for Pharen is at http://scriptor.github.com/pharen.
As of now Pharen covers most of what you could do with PHP. Tail recursion is transformed into reasonably efficient looping, OOP support allows for easily working with existing PHP libraries, and macros provide a ton more opportunities.
If you have any questions, feel free to message me on Github, email me at tamreen.khan@gmail.com, or drop by the IRC channel at #pharen on irc.freenode.net.
If you'd like to contribute, check out the contribute page on the docs site.
Compatible with PHP 5.5.