XMLHttpRequest is becoming a powerful tool. Used in Javascript to get data from the server without a page refresh, it's power can be seen in tools such as Google Suggest. Before there was Google Suggest there was LiveSearch which many people have implemented in their blogs. Here's some sites that may help explain how to use it better:

You can get the code at most of these places in PHP so it's easy to integrate with Library sites or other projects. A nice way to help people get suggested search terms. I'm trying to find a good thesaurus for a similar project. More later.