I plan to put together a comprehensive Golive check sheet covering SEO and site setup generally - but in the meantime here are some useful steps to remember:
Decide if the site will allow users to register - Check the User Management->User Settings to be sure you have configured it correctly.
Delete the .txt files (CHANGELOG.txt, COPYRIGHT.txt, INSTALL.mysql.txt, INSTALL.pgsql.txt, INSTALL.txt, LICENSE.txt, MAINTAINERS.txt, UPGRADE.txt) - See Securing access to files on your website for more about securing your site
Disable unnecessary modules.
Setup Search 404
setup redirects (www. etc)
setup and test contact forms
Setup and administrator role and create a user with this role. Use the AdminRole module for this (http://drupal.org/project/adminrole) that way you don't have to keep adding the permissions - note this is included in 7
Consider blocking the user1 admin user (Use cautiously as some modules may require impersonation master user)
Set up deny rules for certain user names (e.g. root, admin, webmaster etc) - This will stop people registering as webmaster and the like. It will also help to disable logging in as admin - so be sure to do step 7 correctly and test before you disable the admin super user and create a deny rule.
Remove test content (hello world posts etc)
If you are using the transliterate and path auto modules, upload and rename the example i18n-ascii-example.txt -> i18n-ascii.txt in the pathauto module folder to allow pathauto to transliterate extended chars in URLs.
Set up CRON
Enable Caching once you have the site working
Update the theme for your maintenance page (see Customising your Drupal Maintenance page)