(necro)Posting in a legendary thread, wewt.
Just some extra trivial stuff
Cover - Was much improved in FF5 over Cecil's Cover in FF4, in the fact that it was in inherent ability that you didn't have to waste a command selecting in battle. I think it only worked when your allies were low on HP, though. Same deal in FF6 by using the True Knight relic, and FF7 using the Cover materia. If you got the Cover materia up to master level, you would take EVERY physical hit directed at your allies, even if they had full HP.
Corsairs/Pirates - If you're only considering job abilities, the introduction was rather recent with FF6's Setzer. If you're talking storyline wise, you've got pirates lending you use of their ships in FF1,2,3,5,6,9, and 12; and joining your party in 2,5,6,9, and 12. zoogelio made a great post on the history of pirates, just wanted to add that vikings could also be considered pirates of sorts. Bikke is a viking name, and I think there was an old manga with a pirate character named Bikke (supposedly an inspiration on the creator of One Piece).
Samurai - Tsukinomahou wrote "They could also throw gil at all enemies, dealing heavy damage. I assume this was a joke that certain Samurai could "throw money" at their problems and make them go away." This ability is actually a reference to Zenigata Heiji, a fictional policeman of the Edo period, who would catch crooks by throwing coins at them.
http://en.wikipedia.org/wiki/Zenigata_Heiji
Nothing else to add, really, besides to mention some jobs that should be in FF11:
Geomancer - Just for the sake of FF5 style AF pajamas ^^ I suppose having a set of abilities that change depending on the area would give this job a lot of different strategies and playstyles.
Dancer - Could see this as a sort of uber-thief, with lower att/def and even higher acc/eva, and the ability to massive damage once in a while, maybe some kinda buffs, and a Charm that works on beastmen (and other players in PvP) to make things even more interesting. Oh, and the AF would be sexy on both men and women <3
Berserker - Might be tricky to implement this one. Maybe as a slower/stronger alternative to MNK, doing big damage at the expense of not being able to select any other commands once auto-battle has been engaged? Could be a very nice sub for WAR, too.
Chocobo Knight - LOL, just kidding. But it would be kind of cool to have job specific abilities when riding a chocobo. Like some sort of jousting minigame for DRGs and other polearm-using classes, or for RNGs, hitting an offshore target while riding past, Yoichi-style. I dunno ;-p