which can be found:
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\Ontolica for the SharePoint English installations
Ontolica SearchBox Code
By adding a new variable and some new lines to the already defined html variable.
For example, if one would like to add AOL as new external search options one would have to replace the code above with the one specified in the following lines.
In addition, one would also need to make sure that an aol.png 32×32 pixels icon has been added to: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Ontolica\ folder (for the SharePoint English installations).
The last step is clear the cache of the browser and tests the newly added functionality.