granting all to user

Can I grant a user all privileges to all the tables without having to type a
grant command for each table individually?

I know that I can use:
grant all on object to username

but I would like to set this person up as a superuser for now so that he can
assist with development.

It appears that when I set up users the default is NOT to give them access
to any of the tables. I would like to have the default set so that users can
read all the tables and then have the option to give this one particular
person full access.

Any suggestions???
thanks
Jodi