I saw this thread on a different message board, and I thought it would be fun to bring it here. The title says it all... So have at it!
My favorite would definitely have to be Indy, with Sallah (a.k.a. John Rhys Davies) doing the spieling... great dialogue in that little movie!
My other favorite safety spiel is short and sweet, and no longer used... its the classic "Remain seated please. Per mene se sentados por favor." (Pardon my typing of the Spanish language... I am not experienced in doing so, so please bear with me there )