At the office we are talking about an interface on our web application, which has ajaxified checkboxes: you click it, and the change is live. No "action" is performed other than changing data on the server. One group doesn't like this and prefers a submit button, and others of us prefer the ajax version.
This got me to thinking about when to use both, and my intuition says that the ajax version is better for one-off operations, whereas a submit button is better for batch operations where the user will change a number of the check boxes at once, and then hit 'go'. I'm not much of a designer though. Any thoughts on this issue?