It has been mentioned before that if you add up all the letters in the title of the pope that translate into Roman numerals, the total comes out to 666. That title is Vicarius Filii Dei, which is Latin for Vicar of the Son of God. (Incidentally, the Anglican church still uses the term 'vicar' to refer to their clergy, but that's beside the point.)
Now the original statement is only true if you use the old Roman font and spell this title Vicarivs Filii Dei. (If you read a 1611 version of the KJB, the j's are always i's, and the letters u and v are frequently [nearly always] interchanged.) Here's how it works:
V = 5
I = 1
C= 100
A = 0
R = 0
I = 1
V = 5
S = 0
F = 0
I = 1
L = 50
I = 1
I = 1
D = 500
E = 0
I = 1
So, you have 500 + 100 + 50 + (2 x 5) + (6 x 1) = 666
No great earth-shattering revelation here, but it IS interesting...