A PHP-based Operating System?
How does that sound? Crazy, huh... Well, ofcourse it's crazy... But that doesn't mean you can't try to mimic an OS! And that's exactly what EyeOS does... It's 'a free, cross-platform Personal Content Manager System based upon the style of a Desktop Operating System.' Written in PHP, it is quite a nice little project and it is quite fun to play around with the demo, also cuz it has a few 'application's that you'd also find in yer standard OS. Unfortunately, or is that fortunately?, it doesn't seem to run too well on IE cuz of CSS-related issues, but you can't have it all, can you?