Hi, I think a cool feature for the jquery ajax functions would be to specify a delay in milliseconds.
So that when the ajax response is received, jquery checks this timer and waits before triggering the callback. Why? Because with ajax it is very common for people to use "Loading..." messages or animated gifs. In the event that the ajax response is really fast, this can lead to the messages flickering in and out on the website / UI. I believe that it can be annoying to the user to see messages appearing and disappearing really fast. Perhaps the user wonders what the message actually said. I think it's better usability to actually force a delay of atleast 2 seconds, so the "Loading.." message has a chance to register on the users brain, rather than appearing and disappearing in an annoying fashion before they can lock on to it. Right now i'm coding this in myself where appropriate but I think it would be a logical addition to the core because ajax and "please wait" messages go hand in hand, and thus this feature is something continually needed.
