Uematsu combo! xD
FFI, FFII, FFIII, FFIV, FFV, FFVI, FFIX:
"Battle Theme" (only the intro, by Uematsu) and "Battle of Evermore" (Led Zeppelin):
http://youtube.com/watch?v=SplNqFfSAhc
FFV:
"To the North Mountain" (Uematsu) and "Fanfare for the Common man" (Emerson, Lake & Palmer):
http://youtube.com/watch?v=WMtgYccv30U
"Toccata", "Hoedown", "Trilogy" and "Knife Edge", are, among others, songs by ELP that you could hear in a Final Fantasy game...
FFVI, FFIX:
"Terra's Theme", "Vamo' alla Flamenco", "Limited Time", "Black Mages Village" (Uematsu) and "La Folia" (unknown composer, more info here: http://www.folias.nl) But I think the main inspiration for Uematsu was "Conquest of Paradise" (by Vangelis, who also used the Folia chord progression...).
http://youtube.com/watch?v=ExqC2T232sk
FFVII:
"Debut" (Uematsu) and "House of the King" (Focus):
http://youtube.com/watch?v=H2HoM41iZys
(ignore the video, just listen to the music)FFIX:
"The Evil Mist's Rebirth" (Uematsu) = "A Salty Dog" (Procol Harum) + "Watcher of the skies" (Genesis)
http://youtube.com/watch?v=ylzCPwCKn1c
http://youtube.com/watch?v=rq5vFpGD_so
And the list goes on...