During the Credits
There is Greek artwork from the game shown bordering the credits.
After the Credits (spoilers)
There is also an extra scene after the credits that shows the spot where Kratos kills himself after his final battle with Zeus; but now the spot where Kratos was shown lying dead at the end of the game is now a vacant pool of blood with no sign of Kratos. The camera slowly pans away to reveal a path of blood as if Kratos has gotten up and walked away or possibly carried away by another.
The path of blood ends at the edge of the highest mountain in all of Greece (Mount Olympus) where the final battle with Zeus takes place, as if Kratos has jumped off and left the world in chaos but with hope. Which is exactly how the first game starts off, Kratos standing at the edge of what the narrator describes as the highest mountain in all of Greece and jumping off to what he believes is his death. Check out the videos below of the start of the God of War, the start of God of War III and the post-credits scene after the credits of God of War III.
Unlocking the platinum trophy also provides players with a link to a mysterious website with “Spartans stand tall” in the address. Check out the site here: http://www.godofwar.com/spartansstandtall/
Update: The mysterious site’s countdown has ended and revealed a new PSP game called God of War: Ghost of Sparta.