what you need, my friend, is the jQuery UI’s autocomplete.
by the way, this is the class to get rid of that ugly blue hover state for the dropdown:
.ui-state-active,
.ui-widget-content .ui-state-active,
.ui-widget-header .ui-state-active,
a.ui-button:active,
.ui-button:active,
.ui-button.ui-state-active:hover {
background: none;
background-color: #6F257F;
border: none;}