blogapi_update_6001 in modules/blogapi/blogapi.install
Add blogapi_files table to enable size restriction for BlogAPI file uploads.
book_update_6000 in modules/book/book.install
Drupal 5.x to 6.x update.
drupal_install_schema in includes/common.inc
Create all tables that a module defines in its hook_schema().
locale_update_6000 in modules/locale/locale.install
{locales_meta} table became {languages}.
openid_update_6000 in modules/openid/openid.install
Add the openid_nonce table.
openid_update_6001 in modules/openid/openid.install
Bind associations to their providers.
system_update_6020 in modules/system/system.install
Create the tables for the new menu system.
system_update_6021 in modules/system/system.install
Migrate the menu items from the old menu system to the new menu_links table.
system_update_6030 in modules/system/system.install
Add the tables required by actions.inc.
system_update_6036 in modules/system/system.install
Change the search schema and indexing.
system_update_6054 in modules/system/system.install
Add semaphore table.
update_create_batch_table in ./update.php
Create the batch table.
update_fix_d6_requirements in ./update.php
Perform Drupal 5.x to 6.x updates that are required for update.php to function properly.