DocumentClouds VisualSearch.js. Interesting JavaScript library that implements a quite powerful search field - you can search for normal texts or for facets of the data (i.e. specific fields such as title or author) with automatic completion for these fields. This is particularly interesting for document search in semi-structured data sets and the presentation in the browser is nicely done. Good compromise for search fields into which you do not just want to put simple text searches like Google, but possibly also restrictions on metadata, without the user having to know all the options for metadata by heart in their exact syntax.