Roadsend PHP is a free, open source implementation of the PHP language. It includes a compiler that produces native binaries (no interpreter required). Roadsend Compiler can build online web applications with Fast/CGI, offline web applications with an embedded web server (MicroServer), and console applications.
You can find more about our latest efforts, which include a rewrite in C++ using LLVM for JIT and native compilation, on the Roadsend PHP: Raven development site.