(1) Create Custom META and title tag - You can improve the SEO settings with this free SEO extension for Joomla 1.5.The SEO extension allows you to gain fully control over the META and title settings in the http header settings in Joomla 1.5 generated pages
(2) Google Sitemap - This extension used to integrate Google XML sitemap for more advanced Google indexing
(3) Simple SEO Plugin - This extension helps to receive instant feedback on what search engines really think your content is about.
(4) Search Engine Friendly (SEF) URLs - This extension enables Search Engine Friendly (SEF) URLs for categories & businesses names.
(5) SearchCloud and Lists - This module generates a Cloud or a List of popular search strings.Also we can set the number of items that will randomly appear at each page refresh.