VisualSearch.js enhances ordinary search boxes with the ability to autocomplete faceted search queries. Specify the facets for completion, along with the completable values for any facet. You can retrieve the search query as a structured object, so you don't have to parse the query string yourself.
Combogrid, like autocomplete, when added to an input field, enables users to quickly find and select from a pre-populated list of values as they type, but in a tabular and paginated manner. Combogrid provides keyboard navigation support for selecting an item
jQuery.suggest, a simple inline autosuggest jQuery plugin. It takes an array of terms as haystack and suggests the user the first item that matches what has been typed to this point. The suggestion is updated with every keystroke. Tab or Enter will accept the suggestion and update the input field accordingly.