Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
SearchSpring - SearchSpring is an eCommerce site search tool.
Findify - Personalized eCommerce tool
SearchBlox - SearchBlox is an out-of-the-box Enterprise Search Solution built on top of Apache Lucene/Solr.
Queryly - Queryly Search Cloud helps readers find more relevant content instantly on the site.
Hulbee Enterprise Search - Hulbee Enterprise Search is another powerful site search solution that intelligently retrieves information and documents regardless of their source or location.