The EasyGoogleCSE module allows for simple integration of a Google Custom Search Engine into a Joomla website.
It's a standard Joomla module installed via the Joomla Extensions Manager and it's only requirements are that you have setup a Google Custom Search Engine.
This module allows you to create a CSE that uses the overlay method (a lightbox effect overlayed over your website and hosted by Google) or a results page (i.e. Google CSE will send your users to a page on your website to display the results). To have the results displayed in a page of your site is easy using EasyGoogleCSE.