I am not discussing about integrating Google Custom Search in your WordPress site, I already posted a tutorial for that and that requires few more steps and usage of tags, even if you use some plugin then also you have to get custom search ID from Google. Here is one more option you might like.
Search by Google is a WordPress widget plugin. You can add your site name there in the widget and next time whenever anybody searches anything on your site it opens Google site search on Google.Com and displays all results there. This plugin is different because it doesn’t requires Search engine unique ID etc and this is because it doesn’t uses it. It redirects your search results directly to Google.
Usage: Install and activate it. then drag its widget to sidebar from Dashboard -> Appearances -> Widgets page. Widget options include:
- “Title” (leave blank to show only search box not title)
- “Submit button text” (if left blank, “Google search” text will be used)
- “Search on the particular site” (if left blank, Google will search on current site)