When I was writing Windows file systems for living, I played with the Dokan library. Played is a very good word, it's a toy, at best. And maybe even that's an overstatement.
Implementing bind in a file system filter is easy, as far as writing Windows filesystems goes, but unfortunately to be able to hand it to people you need to pay around $400 to some certificate authority to sign your kernel mode driver, else Windows won't load it. If you're the only user you can add yourself as a certificate authority, and you can use your own work for free.
