I put the HTML5WOW 3D filesystem visualizer demo online at fhtr.org/wfsv. Works only on Chrome as it uses the file input webkitdirectory attribute to recursively list directory contents.
Use the file input button in the top-left corner to select a directory to visualize. The visualizer tries to generate a model of the full directory tree, so it only works on small dir trees (less than 500 files or so). Use the console to navigate by clicking on file names. You can also use some shell commands like ls, cp, rm and mv. The filesystem contents aren't modified though, only the visualization.
Here's a video of the visualizer in action from the Google I/O 2011 "HTML5: The Wow and the How"-presentation: