Here's a simple client-side data example (which uses one of the CF8 example databases, so this should work for you as is):

This form displays a simple text box, but as text is entered, suggestions are displayed. The list of suggestions are passed to the autosuggest attribute which accepts a comma delimited list. The list could be hardcoded, but here ValueList() is being used to dynamically build a list based on a prior database lookup.

This is not an Ajax control in that lookups are not asynchronous, there is no communication back to the server to retrieve data, all data is local. This is actually a preferred form of auto-suggest for smaller lists.

For longer lists asynchronous interaction is indeed preferred, and the auto-suggest control supports this by allowing asynchronous calls to a ColdFusion component. Here is a sample CFC:

This CFC has a single method named lookupArt which accepts a string and performs a query to find all matches that start with the specified value. Auto-suggest requires that results be returns in a single dimensional array (for now, hopefully this will change before we ship the final product), and so the code populates an array with the results which are then returned.

Now for the modified form code to use this CFC and method:

Here the autosuggest points to a CFC, and as the CFC (I named it art.cfc) is in the current folder, no path needs to be specified. When a user enters a value, generated JavaScript code triggers an asynchronous calls to the lookupArt method in art.cfc. {cfautosuggestvalue} gets automatically replaced with whatever value the user has entered, and that value is then used by the CFC in the lookup. When an array of results get returned the auto-suggest list gets populated.

Auto-suggest does not get any cleaner and simpler than this.