I just stumbled upon RailsFS. Nice.
RailsFS is a filesystem that maps the ActiveRecord classes in an Rails app as a Linux filesystem. It's written in my new favourite language Ruby and uses FUSE and a Ruby binding for FUSE. It's almost no code, impressive.
Actually, I wrote a very similar filesystem JCFS (Java Class FileSystem) about a year ago also using fuse and some very ugly JNI hacking. JCFS lets you mount Java classes and access class variables and run class methods.
Never really got around to writing a paper or even making the code remotely readable. But hey, you can download it and play with yourself if you're curious.
It release a readable and maybe useable revision of the code soon. Promise.
I will save a discussion about the deficiencies of FUSE (and the merits of Nimloth) for an other post someday...