Kain's Lance: a weapon of Freya's, derived from Kain Highwind from FFIV.
Asura's Rod: also from FFIV, a summon.
In Tetra Master, a few cards have been mentioned already, such as Namingway and Fat Chocobo. There's also the Airship, which is FF1 sprites, as well as FFV's lead chocobo, Boco. Boco shows up twice in this game, actually. He's also the baby chocobo the Black Mages are raising in their village, which they name Bobby Corwen (BObby COrwen).
The song "A Wicked Melody," which plays often when Kuja's around, is a pretty direct take from FFVII's Shinra Theme.
It might have been mentioned in this thread, but of course, the Four-Armed Man, aka Alleyway Jack, is Gilgamesh.
The Antlion makes a return here, who was also a boss in FFIV.
The summon Madeen was first shown in FFVI as Maduin. Maybe coincidentally, the name of the home of the summoners is Madain Sari.
Garnet's real name is Sarah, who was a princess in FFIII.
Along with Une's Mirror and Doga's Artifact (which have already been mentioned) at the auction house (which is itself a carryover from FFVI), a Rat Tail is also up for auction. The Rat Tail has shown up from time to time (most notably in FFI and FFIV).
Ipsen's Castle is pretty similar to the Magnetic Cave in FFIV. In that cave, you have to make your party weaker by removing all metal weapons and armor. In Ipsen's, you have to equip the weakest weapons to make your party strong again.
Garland's lair is called Pandemonium, which, if memory serves right, was also Emperor Palamecia's palace's name.
One of the final bosses is also from FFVI, only in that one, Deathguise was called Doom Gaze.
Armodullahan: also in FFVI, which attacks Locke and Celes, called Dullahan then.
Just a few more things for the list...
Linear Mode
