jQuery

Immediate hide/show

$("#box").hide();
$("#box").show();
$("#box").toggle();

Hide/show with style

$("#box").hide("slow", "swing");  //linear and swing available easing
$("#box").show("fast");
$("#box").toggle(1500, "swing");

Slide

$("#box").slideDown("slow", "linear");
$("#box").slideUp("fast");
$("#box").slideToggle(1500, "swing");

Fade

$("#box").fadeIn(200, "linear");
$("#box").fadeOut("fast");
$("#box").fadeToggle();
$("#box").fadeTo( "slow", 0.33 );