Banner Picker in jQuery
You don't need to wrap your JQuery code in $(document).ready(function() { ... }). See this Stackoverflow question here for more details on that.

The general style for brackets is that the open bracket is on the same line of the declaration, like this below example.

function f() {
    ...
}


Other than that, there's not much else here that I can see that's glaringly wrong, or in need of review. If there's anything else that you want me to cover, just ask, and I'll see what I can do.