Afuse is an automounting file system implemented in user-space using
FUSE. Afuse currently implements the most basic functionality that can
be expected by an automounter; that is it manages a directory of virtual
directories. If one of these virtual directories is accessed and is not
already automounted, afuse will attempt to mount a filesystem onto that
directory. If the mount succeeds the requested access proceeds as normal,
otherwise it will fail with an error. 

The advantage of using afuse over traditional automounters is that afuse
is designed to run entirely in user-space by individual users. This way an
automounting action can take advantage of the invoking users environment,
for example allowing access to an ssh-agent for password-less sshfs
mounts, or allowing access to a graphical environment to get user input
to complete a mount (i.e. popping up a window asking for a password).

WWW: http://afuse.sourceforge.net/