XI's system has 22 unique jobs, and then each of those can strap on any of the other jobs as a "support" job and gain exactly 1/2 of the subjob's abilities, traits, and spells. So I usually run around as a 99 bard with the support job of 49 white mage. Or 99 thief with a support job of 49 dancer.Or a 99 blue mage with a support job of 49 ninja.
The system allowed for an amazing amount of flexibility and made it so jobs could adjust their skills and abilities to each situation. Each job could strap on any of the other jobs as a subjob, although in reality only 2-3 are used on a regular basis.