The main googleajaxsearch module allows you to add searchers over a number
of Google services (Web Search, Local Search, Video Search, Blog Search, News Search, Image Search, Book Search and Patent Search).
1) copy the googleajaxsearch directory into the modules directory
2) Get a Google Ajax Search API Key at http://code.google.com/apis/ajaxsearch/signup.html
3) enable the 'googleajaxsearch' module in drupal
4) edit admin/settings/googleajaxsearch to include the key you received from google and
set number of searchers on page.
5) configure searchers at: Home > Administer > Site building > Blocks
Each searcher is recognized as a block (e.g. Search block 0). To configure it select 'configure'.
There is only 'administer googleajaxsearch' permission added by this module. Any other user-access permissions could be set in block configuration of searcher.
You can write your own plugin for googleajaxsearch. Plugins system works by returning additional keywords from each enabled plugin and adds them to searcher textfield. Keywords from separate plugins are 'AND'-ed. Each keyword in plugin is concatenated by plugin-specific word. E.g. 'gaskeywords' plugin concatenates keywords with 'OR'. Check pluginsAPI.txt in module directory for more info about writing plugins.