Autocompletion

Autocomplete Locally with:

<label for="bands_from_the_70s">Your favorite rock  band from the 70's:</label>
<br />
<input id="bands_from_the_70s" autocomplete="off" size="40" type="text" value="" style="" /></p>
<div class="page_name_auto_complete" id="band_list" style="display:none"></div>
<script type="text/javascript"></script>
<script type="text/javascript" src="autocomplete.js"></script>

new Autocompleter.Local('bands_from_the_70s', 'band_list', [...])
Your favorite rock band from the 70's:

see here

The Ajax autocompleter looks like:
new Ajax.Autocompleter("autocomplete", "autocomplete_choices", "/url/on/server", {});