Every now and then you may need to use a Sprite or MovieClip with a EventListener. And chances are that 99% of these times it will be a MouseEvent, since these objects are easy to place in custom classes and build an entire interface with Actionscript... at least that will be 100% of the times for me ;)
So in these cases you don't want to make Button objects, but still be able to feedback the user that in "this" object contains an action with the mouse.
Well simply placing three lines of code you can show your user the hand cursor (like it appears in a web page), and have the behaviour of a button. Furthermore the third line prevents the hand cursor not to be active if the button has text in it. Those lines go like this:
var button:MovieClip = new MovieClip();
button.buttonMode = true;
button.useHandCursor = true;