The following 5 lines are repeated across applications and plugins again and again. I propose to add a plugin method to jQuery core to reduce these to simple one liners:

$(".selector").hover(function() {
  $(this).addClass("class");
}, function() {
  $(this).removeClass("class");
});

Plugin method and usage:

$.fn.hoverClass = function(hoverClass) {
  return this.hover(function() {
    $(this).addClass(hoverClass);
  }, function() {
    $(this).removeClass(hoverClass);
  });
});
$(".selector").hoverClass("class");