Shoutbox

the basic idea behind it is

you add an event listener to the testbox ( on the keypress event)
in that callback you use xmlhttprequest to pull the data from the server and then you display it in a div under the textbox

theres quite a few premade scripts of this already

if you want to use jquery theres a plugin to do this

download jquery
download jquery.suggest

then add this to your page (assuming the search box id is suggest)

code:

---

$(function($){

$("#suggest").suggest("files/search.php",{
onSelect: function() {alert("You selected: " + this.value)}});

}

---