Autocomplete is yet another good example of a feature that was traditionally used only in desktop applications. Popular implementations of this feature in web applications are very recent. (Note that the typical form autocompletion in web browsers, or the remember-password feature, is implemented locally by the web browsers, it’s not a feature of the site.)
It’s all about enriching web applications’ user interfaces with features that have already been integrated into desktop applications. See a nice autocomplete example that implements this feature at http://demo.script.aculo.us/ajax/autocompleter.
The most popular example of this feature is Google Suggest.
Why Google Suggest? Because it is the most popular web implementation of suggest and autocomplete using AJAX. Believe it or not, Google was not the first to implement this technology. Christian Stocker used it in his Bitflux Blog http://blog.bitflux.ch/archive/2004/07/13/livesearch_roundup...