posixovl is a FUSE based successor of the old UMSDOS. It has a goal to provide POSIX file system functionality on top of vfat. Its code is nice and well written, but its feature set is not complete yet. It just supports: POSIX modes and user/group, hard and symbolic links, device nodes and named pipes.
Much more can be done:
acurrate time stamps
support for local time stamps => UNIX time conversion with DST heuristics
support for obscure characters in file names allowed by POSIX but not allowed by underlying file systems
case sensitivity without clashes
shortname case sensitivity without clashes (independent of shortname= option)
long names without risk of overflow (and long names even on top of 8+3 file systems)
support for file systems that don't support files starting by dot
per volume configuration
implement checks for per volume configuration
ctime, mtime, atime
This project is one of its kind!