Looking for an incremental matching control

Hi I want to add a control to an HTML page that incrementally matches user text
input against a list of options. When the user sees the option that they want
they can click eg a GO button to open that topic. I don't really mind if the
list appears in a box on the screen (like a dropdown list) or if it's only the
best match that appears in the field. Can anyone help me? Cheers J.