Well, done a bit more work on the LCGI plugin. It now handles errors and some corner cases. It is pretty functional and I'm using it to develop some web apps. Still doesn't work on Windows though; that is probably the next task to complete. Unfortunately, that requires that I install a Windows system:-(

LCGI: First version uploaded to github

Just uploaded the first version of my local CGI extension to firefox.

This extension allows open a CGI script residing on your computer. The script is executed and the result is displayed as if you had accessed the script via a remote web server.

It currently is pretty limited:

• It is currently little more than a proof of concept.
• It only runs on Linux. It might run on OSX, and definitely doesn't run on Windows. (I don't have suitable machines to develop and test those versions.) But it should be relatively straightforward to extend this to run on those platforms.
• It probably only works on Firefox 3. In fact it probably only works in a nightly build - I did my development against Firefox head.

Next steps:

• Check if prepackaged versions of the extension works with released versions of Firefox.
  
• Extend the extension to other platforms
• Start using nsIProcess2 when that becomes available.
• Extend nsIProcess/nsIProcess2 to allow one to set environment variables directly (Rather than using the current hack.)
• Implement more of the CGI interface, in particular implement POST requests.
  

Anyway, if you think you might find this useful, need help using it or want to extend it in any way, just drop me an email.

edit: Oops, I should point you at the project page. You can find the code on github:
http://github.com/RufusHamade/lcgi/tree/master
or download the code directly via:
git://github.com/RufusHamade/lcgi.git