How can I add a user as a Site Collection Administrator on my SharePoint Services 3.0 site

From mail2web.com Wiki

Even though a user is defined as an Administrator, they will not have permission to access Site Collection options in your SharePoint™ 3.0 Site. To allow site collection access to a user, you will need to log in with your sharepointadmin user, which was created when your account was first activated. Please refer to the email which was sent to you when your account was first activated to confirm the username and password. Follow these steps to grant a user Site Collection Administration permission:

  1. Log in to your SharePoint Site as the WSSAdmin user
  2. From the Site Actions menu select Site Settings
  3. Under Users and Permissions click on Site collection administrators
  4. Type in the username of the other person you want to make a site collection administrator. You can separate multiple usernames with a semi-colon.
  5. Click on the 'Check Names' icon to confirm that you've entered the username(s) correctly.
  6. Click OK to finalize your changes.

The user is now a Site Collection Administrator and will now have permission to access any administration area of your SharePoint site.

It is recommended that you grant this type of permission with caution, as a Site Collection Administrator will be able to delete any page, sub-site, document, workspace, list or document library that they wish, as well as access and modify the site with SharePoint Designer.