monline

MacFUSE is a native Mac implementation of FUSE (Filesystem in Userspace). It's core is developed quite differently from the original FUSE (on linux), but since it aims to be API-compliant with it's predecessor, a number of FUSE filesystems can be easily ported to MacFUSE.

However there're quite a lot original Mac ideas for new filesystems too. Eg. the Spotlight FS, the AccessibilityFS or GrabFS. You might want to check out YouTubeFS too.