> Is this what you're talking about too?

No, mud-daubers build their mud-nests...well,
not exacltly hanging from something, but sort
of attached. It almost looks as if someone
took a glob of wet mud, threw it into the corner
where a wall meets a ceiling or windowsill,
and let it dry there. Only it has little holes for
the wasps to get in and out. Obviously not the
same as one of your dirt-dobbers.