I was searching looking for the PRIVILEGES that comes with the primary MySQL account on RDS, but it looks like this is not documented anywhere nor blogged about yet. So for the sake of other users, here it is:

GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, RELOAD, PROCESS, REFERENCES, INDEX, ALTER, SHOW DATABASES, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER ON *.* TO 'revin'@'%' IDENTIFIED BY PASSWORD '*xxxxxxxxxxxxxxxxxxx' WITH GRANT OPTION

In case you ask, for what, I was looking for what privileges I can grant other users via the primary account.