There is only one file type that uses the .NEXE extension:
Chrome Native Client Executable
Executable file used by the Google Chrome Web browser; contains an executable that can be run by the browser's Native Client (NaCl) component, similar to how an .EXE file is run by Windows; allows native compiled code (written in C or C++) to be run in the browser quickly and without incurring much overhead.
NEXE files are often used by game developers when porting their code so that their games can be run within a Chrome extension. Some games listed in the Chrome Web Store use native executables.
NOTE: The Native Client project is an open source effort that provides the Native Client Software Development Kit (SDK) for creating NEXE files.
Updated: July 27, 2012