phc-win is an open source PHP compiler for Windows. It compiles PHP scripts to PHP-native bytecode and then produces an EXE file containing your compiled code.

HHVM

    Wikipedia, GitHub
    formerly HipHop for PHP
    virtual machine (with JIT compilation to native code) and compiler to its bytecode
    preceded by (as of early 2013) discontinued HPHPc that compiled to C++
    developed by Facebook

Phalanger

    CodePlex (download), Wikipedia
    compiles to .NET (CIL)

phc

    compiles to native binaries
    not very active now (February 2014) – last version in 2011, last change in summer 2013

Roadsend PHP Compiler

    GitHub, GitHub of a rewrite
    free, open source implementation of PHP with compiler
    compiles to native binaries (Windows, Linux)
    discontinued since 2010 till contributors found – website down, stays on GitHub where last change is from early 2012

bcompiler

    PECL extension of PHP
    experimental
    compiles to PHP bytecode, but can wrap it in Windows binary that loads PHP interpreter (see bcompiler_write_exe_footer() manual)
    looks discontinued now (February 2014) – last change in 2011

Project Zero

    Wikipedia, IBM
    incubator of changes for WebSphere sMash
    supported by IBM
    compiles to Java bytecode
    looks discontinued now (February 2014) – website down, looks like big hype in 2008 and 2009

Bambalam

    compiles to stand-alone Windows binaries
    the binaries contain bytecode and a launcher
    looks discontinued now (February 2014) – last change in 2006

BinaryPHP

    compiles to C++
    looks discontinued now (February 2014) – last change in 2003