The Features includes Very fast search speed, Wildcard and Boolean operator support, Easy installation, Instantly updated searching after a post has been written, Searching of Posts and Pages, Integration into any blog, No javascript / css includes and many more.

Click here for more details & download:

http://wordpress.org/extend/plugins/wpsearch/

Using this WordPress plugin you can add AJAX Search to your site. Version 1 allows for the option of having Blog Search and/or Web Search with another option for a secondary url search, ideally for flickr or another photo stream. Full Style options and Widgetized for you pleasure.

For more details:

www[dot]wordpress[dot]org/extend/plugins/google-ajax-search/

Google Blog Search Preview is a simple plugin for WordPress which displays incoming links from Google Blog Search. This is similar to Technorati incoming links and hence is displayed on the Activity tab of WordPress Dashboard.

Click here to install:

http://wordpress.org/extend/plugins/google-blog-search-preview/