How do I switch a node's view mode for AJAX calls? I've programmatically created a new view mode called ajax.  Is there any way to force a node page to use that view mode if I'm making an AJAX call?  I know how to switch page and node templates when it's an AJAX call in template.php, but it's not quite the same thing.
If you have a custom handler for your ajax request, I suggest you to manually render the node using node_view api function. It has a view_mode parameter which you should set to 'ajax'.