I often have projects that consist of many thousands of extremely small files. It's terribly inefficient to move these around or send them to people as individual files, and inconvenient to be constantly zipping and unzipping and zipping and unzipping to avoid that inefficiency, taking an eternity each time and requiring that extra space.
It would be very useful if I could store them as something like an ISO file, mounting and unmounting them for use but with writability. I can't seem to find any mention of such a thing existing, though, at least with Windows support. Does it? I've resorted to using ramdisk images with ImDisk, which works exactly like I'd want but mounts the entire thing in RAM instead of just accessing a file. Still saves an enormous amount of time, but not as good as just having a file accessed on demand.