Ever consider using Latin or Hebrew, as they were the languages of the time? Here's my favorite, with Barney the purple monstrosity. Take the Latin letters in CUTE PURPLE DINOSAUR, keeping in mind the Romans treated 'U' as 'V'.

C + V + V + L + D + I + V = 100 + 5 + 5 + 50 + 500 + 1 + 5 = 666

If you go the Hebrew route, try the kaballah, the mystical side of judaism where all letters have numbers. It could be fun parsing all the names of people around the world until you get a 666. heh heh...