Yes, I would love to see a regularly updated list of museum exhibition but what
 museums are we talking about? A list of all exhibitions of all museums would
be monumental, no? Not to mention keeping up with it! We can barely keep up
with all the twists and turns of our own exhibition list! Art museums do, at
least the big ones do, periodically release a 6-12 month list of exhibitions
and events. We do. You apply to the public  relations, marketing or public
information departments of each museum.
 
If there IS something on line, I'd like to see it too!